Request extra pages when you get a new passport. You may need to renew your passport, or have pages inserted, as some countries require you to have a minimum number of empty pages. A passport near expiration can be a greater problem because some immigration officials view them with great suspicion. You can save yourself a few hassles if your passport is valid for at least six months longer than the duration of your trip. Keeping them in a Ziploc will prevent the stamps from smearing in case you are in a rainstorm or fall in the water.
Visa requirements are one of the things to talk to a travel agent about fairly early in your planning, as they can be real roadblocks.
For long trips it is better to get your visas as you go, since they can expire after a certain period of time. Be sure you are not required to obtain them in your home country, and that you are able to obtain them from the neighboring countries along the way.
I obtained all of mine on the road since they would have expired long before I got there. Indonesia, Thailand, Malaysia, Nepal, Egypt, and probably Turkey are all given "on entry" or "on arrival" (VOA) for most Westerners. Australia, India, and African countries are the ones you have to wait at embassies for. Pakistan will give you a five-day temporary visa at the border in order to get to the capital. Europe is borderless, so once you are in, you can roam about.
"Sometimes you need to know what approach is likely to get you a visa BEFORE you talk to the embassy. Some countries do not like foreign businessmen, so business people have to say they are going as tourists. Other countries do not give visas to tourists, so tourists have to arrange a sponsor who claims they have business in the country. It is very hard to get a visa to India for research purposes, very hard to get a visa to Iran except for research purposes… If you do not know the proper line with which to approach the particular consulate or embassy, you may blow your chances prematurely." <Edward Hasbrouck>
"Don't ever put work as the reason for your trip, or even mention you might try it unless you are certain you will get issued a visa on this basis. It is the surest way to get refused a visa." <Chris Finlayson>
"A guy I met made a big mistake when entering Malawi: he wrote 'Photographer' on the entry form, and was more or less expelled from the country a few days later, after endless hassles, when he tried to explain that he was just taking photographs of nature, and was not a journalist bringing home articles about the political situation in Malawi. Never EVER put down 'photographer', 'journalist', 'author' or anything similar." <Mats Henricson>
If you need visas at the beginning of the trip, get them before you leave. The rest you can easily get as you go from the embassies or consulates in big cities, though this can take many days, especially if they have to contact your home country.
"Be sure to find out what days and hours embassies are open. Some embassies and consulates are open for visa applications only one or a few days a week, and then for only a couple of hours. In some countries the requirements change frequently. Talking to travellers who have visited the country recently provides the best information." <Keith Conover>
Some Muslim countries, such as Saudi Arabia, do not issue visas to single women, or issue tourist visas. You will get better specific advice by contacting the embassy in the country of your citizenship.
Many countries will not let you enter unless you have an airline ticket out of the country, and a visa to the next one. Some ask for proof of available funds, or require you to buy a minimum amount of their currency. A credit card sometimes works. It is possible to get extensions. Do not overstay your visa without renewing, unless you want to pay fines and possibly go to court.
"Caution: Some countries, such as Indonesia, will not allow you to extend your visa from inside the country -- you have to leave and then return again with a new visa, which may or may not be available at the border crossing. For trips to Thailand involving exits to other countries and returns, it is best to figure out how many entries you need (not forgetting the first one) and apply for a multiple-entry visa covering all the trips before you get there. Each of the entries is valid for a specified time period, but the overall duration of all the Thai trips is also limited, so you will need to consult with the appropriate Thai embassy for details. You can get a 30-day visa for Thailand at the Bangkok airport, etc., so this is not a problem for short stays in-country. In Nepal, multiple-entry visas or visa extensions are really rather expensive (about $30 US). You can get an extension in-country." <Larry Cotter>
"For proof of funds you can either have wads of travellers cheques, references from banks or building societies, or photocopies of recent statements amongst other things. Be careful when an embassy asks you to provide evidence - some are getting wise to the trick of getting a relative or friend to deposit money in your account temporarily." <Chris Finlayson>
While embassies and travel agents are the surest source of information, travel guidebooks (introductory sections of the Lonely Planet Guide series for example) also have information. Provided the book is reasonably up to date, and no coups or civil wars have since occurred, they are generally correct. Be prepared for entry requirements to change while you are on the road. Take 10 or 20 copies of your passport photo with you, they may come in handy.
"Good places to get visas in Europe are London, Paris, Bern, and Bonn. There are companies that specialize in walking your passport around between different embassies, filling in forms and all such stuff for you. I got the impression they are rather expensive." <Mats Henricson>
"If you need a lot of visas, do not underestimate the time (and expense of Registered Mail) needed to get them all sequentially." <Larry Cotter>
"I obtained the Australian visa in San Francisco in five minutes -- very polite and friendly service. Singapore, Malaysia, Indonesia, New Zealand, Nepal, and Europe "on entry". I also received a Thai visa in Kuala Lumpur in one day with no problems, in order to stay two months instead of one. Got the China and Laos visas in Bangkok through a travel agent to save myself the enormous hassle of running around the massive, congested, and polluted city, and get out sooner -- the visas were expensive. Extended Laos in the north, but don't count on it unless you are in Vientiane. Obtained two 1-month extensions in China, for little cost and no hassle -- actually pleasant to meet the English speakers at the police office for foreigners. Got the Pakistan visa in Beijing in one day. Got the India visa in Beijing, but gouged for "faxing the home country of the USA", plus it was only a three-month 'on entry' visa, which doesn't help when you want to stay six months and they won't extend more than a month, nor is it easy to get a new visa in a neighboring country after that one expires. Best to do it all at once on a six-month, 'single-entry', although I heard you can get a six-month, multiple-entry visa from your home country. They also have a one-year visa, although they will deny it. After being so sick in India, I have a new, self-imposed three-month rule for myself to leave, so it doesn't matter next time! Read the Lonely Planets for the basic info, and check the other guidebooks if you have access. There used to be some info online." <Marc>
Embassies & Consulates Worldwide
Yahoo: Embassies & Consulates
Travisa: Scanned Visa Applications Online
Travel.com.au: Visa Information for any Nationality
Travel Document Systems: Visa Information and Applications
A Briggs: Visa Information
Visa Requirements for US Citizens (not very accurate)
U.S. Department of State Passport Services
U.S. Department of State and Consular Affairs
Government Representations in Foreign Countries on the Internet
Foreign Consular Affairs in the U.S.
U.S. Embassies and Consulates Websites
UK Passport Office
Canadian Passport Office
Passport and Visa Services Companies Listed at Yahoo