General Travel Preparation
Foreign travel is, obviously, different than travel would be within say the USA. Before your trip out of the states (or into the states if you don't live in them), make absolute sure you find out the "rules and regulations" of the country you're headed into.
It's a 99% chance that you'll need a passport when you head into another country- make sure you have one! Make sure that, if you don't already have one, you get it taken care of as soon as you find out you'll be taking a trip- passports aren't made in one day. You don't want to be stuck without one because you waited until the day before to get your snapshot taken- you won't be getting on the plane.
Make sure that you're fully prepared when you go to get your passport- make sure you bring the needed identification (birth certificate with a U.S. State or county embossed seal, your naturalisation/Citizenship certificate), a picture (taken at a "passport shop"), a driver's license or Military I.D. issued over six months ago, a completed passport form and the cash to pay for the passport (I'm not sure what the current fee is since mine hasn't expired, yet, from years ago). If you're passport will be expiring soon (within 6 months) make sure you re-new it - the country you're heading to may not let you in because the expiration date is so close.
Depending on the country you're heading to, make sure you get your visa if it's needed (an endorsement on your passport).
For the country that I visit each year (Sweden), I do need a passport but not a visa because my stay does not extend 90 days (although I wish it would). Make sure that you allow several weeks time if you need a visa - unlike a passport (which can take 3 months to process) a visa may only take a few weeks, but you don't want to take any chances.
Before you go "drug happy" and pack your aspirin for your headaches and your Midol for your cramps, make sure you check out the 'medications' you can bring with you - what may be perfectly fine and legal in the UK, might not be ok for you to bring into a foreign country. Bring the medication in the bottle it came in to prevent any problems. If you're on a prescription for something you have, make sure to bring a doctors note along with it.
Packing - The Usual Stuff
Of course, when packing you'll need to bring the basic things that you would bring whether you're traveling to Florida or South Africa.
It's not wise to forget these, and I'd be a bit freaked out if you did. Pack wisely when it comes to your clothes - there is absolutely no need to pack your whole wardrobe when you'll only be gone for a few weeks.
Make sure that you bring clothes that you can mix and match so you're not stuck with one sweater that will only go with a specific pair of pants- you'll be wasting a lot of room this way. To save some space, pack your socks underwear and bras (and whatever else you can fit) into your sneakers.
Things such as your soap, facial cleansers, hair care products, sunscreen, razor, shaving cream, nail files, nail clippers, deodorant, tooth brushes and toothpaste, dental floss and all of your makeup are things you won't want to forget. Just make sure that you tighten all of the jars, lids and tops - you'll be sorry if your nail polish remover leaks on your favorite shirt. It's a good idea to just take what you need- there's no need to bring along 6 different lip sticks - for a few weeks (or however long you'll be away) you can deal with one or two. Put the things that you can into a small plastic bottle of your own- all of these beauty products and toiletries can be heavy if left in original large sized jars of pumps, etc. If you're staying in a hotel, it might be a wise idea and make a call ahead to them and see what toiletries they have in the bathroom for you.
When traveling to a foreign country, it's obviously pretty stupid of you to bring your Filenes card with you when there isn't one located in Africa. It's also not wise to bring a Discover card because it's probably not accepted. However, do bring your Visa or Mastercard if you have one- this is better to use than cash in foreign countries. Don't forget your traveler's checks if you're using those and your ATM cards.
If at all possible, make sure you can try and avoid bringing any types of products that need to be plugged in (hair dryers, curling irons, alarm clocks, etc). Towel dry your hair instead of blow dry, have the hotel give you a wakeup call instead of bringing an alarm clock. Most of the countries out there use 220 volts at 50 Hertz but some use 110 volts at 60 Hertz. On top of that, all sockets are different and what you plug in at home, might not fit into a socket found in a hotel in India. Of course, adapters and converters can be purchased for this slight problem but it's money and space that's not completely necessary. Camera/Video camera- definitely one of the most important things you can bring along. A foreign trip may be a once in a lifetime opportunity into a world that you'll never venture again. To capture this trip and provide memories, and moments for the rest of the family to see (who weren't as fortunate to go with you) - take a lot of pictures. Don't forget the film!
If you're like me and hate planes, you'll want to bring things to occupy you - if you love planes, you still might want to bring things to occupy you; books, magazines and paper and pen/pencil should keep your attention for awhile. Make sure you bring gum for the horrible ear popping that occurs when you're changing altitudes and getting higher.
Packing is what you make it - if you wait until the last minute and rush around without a list, you'll be stressed out before you even hit the airplane. If you plan weeks in advance, start your list early and pack as close to your leaving date as possible, you'll be less stressed and worried that you forgot something.