Many travelers have a fixed date when they must return home for school or a job. These are generally unavoidable constraints that are a part of your original plans. If you don't have such constraints, then you should be able to make an open-ended plan, even if you originally intend to spend only a couple of months traveling.
I have met many travelers who returned home because of obligations that might have been avoided. They most often involve an apartment that you must pay rent on, or sub-let, or move out of. One fellow had to return because he had left his car with someone who could only keep it for three months. Some people return home just to attend a party, wedding, or reunion. After a couple of months on the Road, it may seem much more reasonable to just send a telegram, but they promised, and now they must be there. Yes, these can be important reasons, and they may be unavoidable, but before you leave home you should consciously recognize every obligation that you have made to return, and convince yourself that it is absolutely unavoidable.
Airplane TicketsFixed Dates -- Avoid buying airplane tickets with fixed departure dates. You will always want to change them. Always. In fact, avoid buying a round trip ticket at all if you can. Many travelers to South America buy round-trip tickets to Lima, Peru. They often have a fixed return date, and the price seems pretty reasonable. This is fine if you just want to visit Peru, Bolivia, and Ecuador, which are reasonably close together. But, no, many of these travelers also want to get down to Chile, Argentina, and Brazil.
On a world map, it seems that you could visit most of South America in three months or so. Maps are small and flat; South America is neither. After traveling slowly down to Rio and Sao Paulo, they suddenly realize that it will take them at least two weeks of the hardest possible non-stop cross-country travel to reach their return flight in Lima. For the first time, that cheap fixed-date round-trip ticket suddenly looks more like a huge stone around their necks than a great deal. Some end up taking an expensive flight back to Lima (if they can get one), which costs them half as much as their original ticket.
Fixed date tickets are often called APEX (Advanced Purchase Excursion) tickets; they are also non-refundable. If the area on your ticket for "Expiration Date" is empty, it almost always means -- no matter what the ticket agent may promise and swear to you on his mother's grave -- that your ticket is an APEX ticket with a fixed return (and probably departure) date. Since you cannot change the return date, there is no need to specify an expiration date. If this is not what you intended to buy, then you have been ripped-off.
Round-The-World (RTW) -- If you have purchased a six-month or one-year round-the-world ticket at home, you can often extend that ticket for six months at a time by paying more money. Get this information before you buy the ticket and learn exactly which offices in which countries will allow you to do this and for what cost. (If possible get this in writing on company letterhead.) Then, at least you have a choice.
Actually, you always have a choice -- some of the choices just seem pretty unreasonable sometimes. You could choose to just throw away the unused portion of your round-the-world ticket when it expires. "WHAT! Throw it away?? Are you crazy?!" Well, it is a choice and you should consider it. You can always sell at least the next leg to another traveler.
In fact, some people have done exactly that, and never regretted the freedom it suddenly gave them. Instead of rushing from country to country, constantly trying to figure out how they were going to squeeze half a world of traveling into the next few months, they just ripped up (or sold) their return ticket, or called the boss to say they would not return for another 6 months (if ever). Then, they went out and celebrated! Suddenly, their lives became simple, footloose and fancy-free! When they removed all of their time constraints, their journey was reborn into true vagabondage, and they never looked back. Think about it.
RendezvousMeeting someone, somewhere, at a specific time: this constraint is a real loser. Sometimes there are (apparently) good reasons for imposing time constraints like jobs or air tickets. But making a promise to meet someone is really putting unnecessary shackles on yourself. Arrange to send messages along the way to determine your mutual whereabouts, so you can arrange an alternative meeting if the first one doesn't work out. Do not make it a hard and fast promise.
If your mother is flying in from London on the 12th, and she is expecting you to meet and take care of her while in Bangladesh, you will feel very obligated not to miss that plane. If you must make these kind of arrangements, plan them for early on in your trip before your schedule goes all to hell. In any case, plan to confirm by direct telephone call a week or so beforehand that both of you will in fact be able to make the rendezvous.
Special EventsThe most common day-to-day constraints that travelers place upon themselves involve trying to be at the right place at the right time. A few of these may be events that you have scheduled your entire trip around, like Mardi Gras, or a total solar eclipse. But every week you will be trying to rearrange your plans to include another festival, market day, or cock-fight. If you find yourself rushing around too much, and abandoning places that you would rather stay in, stop and re-evaluate your schedule. Limit the number of absolute "must-see" events, and try not to let them dictate your pace. Much of the Third World is like a festival every day.
Almost as important is trying not to be in the wrong place at the wrong time. Ramadan in Muslim countries can be difficult, but quite a cultural experience, especially if you are there for the transitions. The best times to miss are long national holidays where everyone in the country is out traveling around. Personally, I try to avoid the biggest festivals like Mardi Gras in Rio or Vera Cruz, the camel festival in Pushkar, or Easter in Jerusalem, where there are so many tourists, and the crowds are just too much for me to handle. You will also have a devil of a time finding a room, or getting transportation in and out.
SeasonsSeasons can certainly make a difference in your trip and you should try to plan for them, but you can't hit every region in just the right season. Places like northern China, northern Pakistan, Korea, Siberia, and southern New Zealand can be a real trial in the wintertime, and Egypt and India will be almost insufferable in the summer. But some travelers do it anyway, and they definitely miss the crowds. In Southeast Asia, the wet season is just a bit more difficult to travel in than the (so-called) dry season. I once visited the Philippines during the height of the typhoon season and had a beach practically to myself. There was just one storm (not a typhoon), and it rained about half of most days. I still got plenty of sun and sea, paid one third of the high-season rate, and enjoyed the solitude.
Nowdays, there is such an explosion of western tourists visiting every place in the world, that I recommend that you consider visiting the more popular areas in their less-popular seasons. Decide for yourself if the advantages of the season are worth the crowds. The best trekking season in Nepal is the worst time to visit its interesting jungle areas; it is also the time when half of the western tourist market descends on Kathmandu and the trails are bumper-to-bumper with rucksacks.
If you travel very long, you will have a few bad times, along with the great ones. One of the great advantages of having traveled a great deal is this: No matter how bad it gets, you can always remember something worse. One of the strange things about the bad experiences is that they are the source of some of the best travelers' stories, and most vivid memories; they are your badge of courage. If you don't have any bad times, what are you going to talk about around the travelers' "campfire"?
I traveled in China for three months in 1985. It was a lot tougher for independent travelers then than it is now. In fact it was a constant struggle to get anything that you wanted -- a room, a meal, a train ticket, or to fight your way onto that train. In all of my months in Asia before and after that, I never, ever met a traveler who was not genuinely glad to get out of China. And I never met a traveler who did not want to go back! Most of us did.
Why? I don't think I should even try to explain. Let's just say that it was an experience imminently worth having. You knew you were alive in China, you knew it every minute of every day. You lived by your wits, your determination, and your stamina. In some ways, it was like traveling in Asia 15 or 20 years ago (only less friendly). When you met travelers, you greeted them on the street, you huddled together, shared scraps of information, swapped wild stories, and grinned about how hard it was. You stuck together, and if times got tough, you just made up for it by enjoying the few little pleasures that much more. After a month or two luxuriating on banana pancakes and Big Macs on the regular travelers' circuits, you hear the Call of the Wild again, and you long to go back to the intrepid places, where you eat the Road for breakfast.
What about the general hassles you cannot avoid? There will be plenty of frustrations on the Road that you would never encounter at home, but try not to dwell on that thought. "This would never happen at home! Back in Freedonia, I can just..." This kind of thinking is about as futile as wishing for your favorite foods, and only leads down the road to self-pity and homesickness. The fact is, you just have to learn to live with a certain level of hassles that you cannot do much about.
You must get used to the problems, and don't let them overpower you. Think of the hassles as natural phenomena; many of them are. Much of what you have to put up with is no worse than what the local people must deal with every day. You will get used to these kinds of hassles as you grow to identify more with Third World people, and see how trying their everyday lives can be, especially compared to your life at home.
In addition, you attract extra hassles by traveling, and because you are a foreigner in a strange land. The bureaucratic hassles of visas, borders, customs, extensions, permits, registration, and passport checks can be as frustrating as anything else; but try to see them, too, as natural phenomena that affect all travelers. They are just humanity's defensive reaction to make it more difficult for strangers to enjoy the wonders of these countries. Always allow ridiculous amounts of time for getting through these obstacles. Some border crossings take all day, so bring a good book and don't let it upset you.
Perhaps the hardest to tolerate are the extra hassles you can get on the streets every day, just because you are a western visitor -- hassles which the locals never incur. Hawkers, beggars, conmen, touts, prostitutes, merchants, and sleazy lotharios may pounce upon you wherever you walk, while local people are left alone. You are overcharged at every turn, while locals pay the normal price. Beggars insult you for being heartless, while local upper-class fat-cats are respectfully left in peace; nobody picks their pockets, it seems!
Fortunately, it is not this bad everywhere, although as Third World people see more and more tourists, they are quickly learning to 'hit us up' us for every dollar they can get. But, yes, this is sometimes the price you must pay for venturing out beyond your horizons. When you find yourself getting depressed about such hassles -- so much that you cannot enjoy your travels -- consider moving on to a new country where things will be easier. If nothing else, this thought may remind you that the places you came to visit are imminently worthwhile, even if you have to suffer through a shitstorm to get there.
In fact, there are many ways in which you still enjoy advantages over the local people in their own country, and I do not speak only of your wealth. In many countries you enjoy a high level of immunity from the uncertainties of life in less democratic states. You can say what you like, dress as you like, travel where you want without getting permission, and even break minor laws without being thrown in jail. When violence threatens, foreigners are usually protected instinctively by the local people and police, who want to avoid bad publicity. And you are footloose and fancy-free -- if you don't like the current place, you can always shoulder your pack and move on to any other place you like.
As a foreigner, your status may be elevated to something between a movie star, or -- as you may sometimes feel -- a side-show freak. Gone is your anonymity, your ability to walk down the street minding your own business without being noticed. You are popular, almost famous it seems; heads turn, children point and scream, adults stop and stare, young people laugh and shout at you. Sometimes it seems that your every move is watched and commented upon. "What are the foreigners doing now?" "They are drinking tea!" "Wow, foreigners drink tea, too? Let's go watch!"
Whether the attention is positive or negative, you will often grow tired of being in the spotlight. Whenever you open your bag, any bag, or just take something out of your pocket on a Chinese train, you will draw a good crowd. They all carry the same little bags when they travel and they all contain exactly the same things. A tin cup, a toothbrush, a towel, a packet of tea, some extra underwear and a light jacket. Whatever you pull out of your bag is going to be something really amazing to them. Crowds still gather around foreigners in China when they stop to inspect a map on the street.
And yet, many foreigners find it difficult to make the transition back to being ordinary citizens when then arrive in a western country. Gone is the attention, the special treatment, good and bad; you are just another ordinary person on the street to be ignored. Although you can't always appreciate it, there is something special about being a star. After years in Asia, I go crazy seeing all the "foreigners" in shops at home, and blonde hair turns my head for weeks after returning.