Finances and Paperwork.
	Portfolio. Time to do a financial risk assessment evaluation and move your millions around accordingly. This isn't nearly as complicated as it sounds (especially if you don't have millions). Basically you want to answer a few questions, like "If the stock market crashes while I'm gone will I be stuck in Katmandu with $2 to my name?" and "If the market triples in the next three months will I watching my net worth accrue at a solid thirty-five cents a month in my bank account?" It also wouldn't hurt to find out how to transfer cash from your assets to wherever you happen to be when you need it most...
	Checking account. There will probably be some bills coming in while you're gone. Unless you're a total recluse, you can find someone from among your friends or relatives who would be willing to pay these bills for you - either through cash you give them in advance, a joint checking account, or (if they really like you) a promise to pay them back when you get home.
	Addresses. Never, ever take your original address book with you. If you are quailing at the idea of having to write to thirty friends a month, consider writing a "newsletter" to a friend who will photocopy it and send it around. It wouldn't hurt to give them mailing labels, etc. in advance.
	Taxes. You can file for an extension that will take you through to August. If you are working out of country for seven months of the year then you may not have to pay US taxes on your earnings. Double check this information. I'm not a CPA.
	Will and power of attorney. It never hurts to have one of these. You should make sure the format fits your portfolio - I once gave instructions to a good friend of mine to invest some of my money in the stock market if it started going up. I left him with a standard power of attorney form. I spent the next six months overseas gloating while the market shot up 30%. I returned to discover that my broker (Schwab) hadn't allowed my friend to touch my funds because they had their own power of attorney form and therefore wouldn't accept mine.
	Health insurance. I struggle with this every time I go overseas. The truth is that Blue Cross/Blue Shield isn't going to be much good in the hinterlands of Kamatchka, and that even if you fall off a yak and break your leg it probably isn't worthwhile showing the local doctor how to write a bill (if indeed he knows how to write) so that you have something which you then must have officially translated into English (for several hundred dollars) in order to get your $3.42 reimbursement. The trouble is that if you get sick or injured and make it back to the States, you will not be able to get insurance coverage and could well be spending your life savings to make yourself well again.
For your trip...
	Tickets. There are many books available on how to fly cheap/free so I won't go into the details here. Generally you will be faced with a time/money tradeoff - unless you are willing to take a six-week freighter to Rio or hang out standby in the airport for a week with nothing more than a toothbrush and a extra pair of underwear in your back pocket then you will probably be paying something for your ticket. I generally look through the Sunday Travel section of a major city newspaper and go through the cheap tickets advertised there (they use major airlines so you don't have to worry about suddenly finding yourself on Urdu Air) . I've also found that the internet has some very cheap fares available although I can't yet vouch for their reliability.
	Passport. You need one of these. More importantly, you need it to be less than six months from expiring. Many countries won't accept a passport that is about to go out of date. If you think that getting arrested may be a part of your itinerary, try to get your visa issued on a separate piece of paper from your passport. Also if you plan on traveling through countries that are unfriendly to each other (ie Israel and parts of the Arab world. South Africa and other parts of Africa, etc.) make sure you get the visa stamped separately.
	Visa. Tourist visas are easy to get but tend to be of short duration. Consider trying to finagle a business visa if you plan on being in one country for any length of time. Travel agencies can sometimes do this for you but it is almost always expensive. Under no circumstances get a journalist visa even if you plan to do some writing/photographing/filming for publication.
	Travelers' Checks. Some countries seem to prefer smaller denominations and some charge you a fee per check so make sure you are getting the right size bills. And bring more than you think you need. You never know when you will stumble upon a ruby mine that needs exploiting or a leopard that needs saving...
	First night's hotel. I used to pooh-pooh people who booked their first night's room in advance. Real travelers don't need reservations, I'd say haughtily. Then I would get on a plane and forty-odd hours later stagger off, grainy-eyed and slack-brained, wanting nothing more than a bath and a place to lay my head. I would pay some cyclo driver an exhorbitant sum to take me on a six-hour search of a cheap hotel. I'd then spend the next three days recovering. Eventually I realized that I was being dumb, and started booking my first night's room.
	Shots (see medical section). Some shots have a two-month lead time so factor this in to your preparations.
	Language (see section). It's awfully hard to work up enough enthusiasm to learn Urdu if you are only going to be in Pakistan for ten days. It's even harder to try to learn the native tongues from all seven of the countries that you are going to be traveling through over an eight-week period. It can, however, make a huge difference if you know even five polite words for each place you're going to be in. There are several relatively painless ways to learn these words such as pinning lists up on the wall across from your toilet (and taking all the books and magazines out of the bathroom) a few weeks before you go.
	Guidebooks/Country history. I always buy these books well in advance of a trip and then get so busy that they end up sitting on my nighttable until the day they get thrown into my carry-on bag. Once I arrive in-country I'm way to busy (and tired) to read them. Long after I've gotten home I pick one up and start browsing through it and spend the next two weeks kicking myself for all the things I didn't do while I was there.
	Manuals. If you buy any new equipment before going (we're talking cameras here, not water bottles) bring the manuals with you. I didn't and I regretted it.
	Equipment. If you think about it several months in advance and look for sales you can save yourself a great deal of money on gear. Borrowing stuff can also cut down significantly on the cost of a trip. Some outdoor equipment corporations will give you discounts if you contact their promotions department and talk fast.
	You can either buy birthday/Christmas/etc. presents for people before you go or bring gifts back with you from your trip or conveniently forget that any holidays happened while you were gone.
	Photos. If you are planning to take photos with you to show people then you might drop by an office supply store/copy shop and have them laminated.
To avoid nasty surprises when you get home...
	Mothball your clothes.
	Return your library books. Those fines can really pile up.
	Pay your parking tickets. They add up too.
	Backup your computer systems.
	Car. What to do with your car? Sell it? Lend it to a friend? Empty the oil, put it on blocks and store it for an arm and a leg? A lot depends on how long you'll be gone. Trusted mechanics tell me that it is generally better to get rid of a car than to let it sit for any length of time. On the other hand, it's awfully nice after a long trip to have your own transport waiting for you.
	Storage. I once packed all of my stuff for a two week trip/move to a new apartment. One thing led to the next and my stuff is still packed - four years later. A year ago I went through it and discovered what happens when you leave a bottle of mustard in a hot attic for too long and exactly how many moths it takes to eat a hand-knit sweater. Now I'm not saying that you're going to take a week-long trip to Tibet, fall in love with a monk, get married and live on a mountaintop for the next 16 years, but you never know.
Optional extras...
	Newspaper articles. Although I wouldn't encourage anyone to embark on a career as a travel writer, your hometown newspaper would probably love to hear from you while you're gone and may even consider publishing a weekly series of letters from your trip.
	Grants. It is sometimes possible to get a grant for your travel if you are doing something fairly unusual. Getting funding is a long and tedious process, however, and usually takes a year or more.
	Peace Corps/NGO's. When I was in the Peace Corps I was so lonely for Western company that whenever I saw backpackers in the town near my village I would invite them to my village, and if they were foolish enough to say yes, talk their ears off for as long as they wanted to stay. Peace Corps and other volunteers are a fantastic way to see a country - they can get you into a village in a way that no tour can possibly match (you will probably be introduced as a visiting relative), will have cultural insights that took a long, hard time to figure out, and will be almost as happy to see you as your golden retriever is when you come home. Remember, volunteers are dirt poor and live at the poverty line, so offer them at least a token amount of money ("token" to you - it will probably be more than their daily salary) to feed and house you. If you bring m&m's and real cheese then you will have made a friend for life. How to find Peace Corps Volunteers? Write to the head country office and ask them to post a letter on their bulletin board. I did this when I was planning a trip to Africa and got 150 responses in the first three months.
	Shakedown hike. If you're planning on doing a lot of backpacking then a short shakedown hike can give your gear (and yourself) a chance to breakdown, change your mind, tear, leak, and rub great gaping holes in the small of your back and the soles of your feet.
Ready to Go?
	Idiot list. My flying buddy and I used to do this before going hang gliding. We would stand next to the car and go through an idiot check. "Hang gliders? Check. Helmets? Check. Harnesses? Check." And so on. Believe it or not, it is possible to spend two months putting together your backpack, get on a plane, and realize in Burundi that it's still on your bed.