Ideally, one of the bank cards should be Visa while the other MasterCard so that no matter what ATM system the country uses, one of them would work. But more importantly, if something happens to one of the accounts (say you made 3 failed attempts to withdraw cash from an ATM and now your account is locked), you can use the other card to bail you out. Otherwise, you'd have to be calling your bank back home, which is likely to be in a different time zone, and they don't believe you since you are calling from an international phone number, and you don't have all the information they require, and it's a huge headache that you'd rather avoid.
To reduce the risk of loosing all of your credit & bank cards due to one unfortunate incident (if you travel long enough, you are bound to be pick-pocketed), have a backup wallet. In your main wallet carry the minimum amount of cache and one credit card. While your backup wallet should have a second credit card, issued on a different bank account, and the major portion of the drawn cash. Leave the backup wallet in the hotel room while shopping so that if you are mugged, you can give up your wallet at hand and still be OK.
While in transit, it's best to have your passport tucked in a secret touch which you don't need to access frequently. For instance, keep your cash separate so that you don't have to fumble with the passport while getting some money for the train ticket. Also, scan in the passport into a JPEG image and email it to yourself. If you do lose everything, the embassy is more likely to believe you if you could at least print out a copy of your passport.
It's a common misconception that if you are traveling with 2 packs, one big pack and one small pack, that it's the big one you have to worry about. In reality, it's much easier to steal the small day-pack right out of your hands and run away with it, as opposed to the big heavy backpack. So you are better off with keeping the camera in the big backpack. In the small pack which youíll be keeping on your lap while on the bus, only keep a hat, a jacket and a guide book.
The beach - don't take anything to the beach with you except whatever you are willing to have stolen. It's as simple as that. There are lots of people who are far poorer than you think it's possible to be. To them, even your old pair of sandals and a towel is worth grabbing while you are enjoying your swim.
The first time I went traveling, I bought malaria pills, antibiotics, diary medicine, etc., got the vaccinations, all of which cost me well over $500US. Little did I know that in most other countries, medication is very cheap to purchase and vaccinations are often free. In fact, sometimes they even administer them right in the airport as you are entering the country. So save your money and take care of this while on the road.
A guide book costs around $25 but the amount of headaches you'll be avoiding by using it will pay itself off in the first day and a half of travel. For example - you roll into a town and as soon as you get off the bus, there are 10 hustlers trying to get your business for x10 times the normal going rate. But if you have a guide book, you already know how much a room costs in these neighborhoods and weather you need a cab or if you can just get there on foot. Everyone has their favorites but I'd recommend "Lonely Planet" or "Lets Go" publications. As far as actual points of interests, guide books are good, but talk to the locals - you'll be able to get even better information and make friends in the process.
If you are traveling in a 3rd world county, haggling over prices is the norm and you should certainly practice doing that. But remember that people there are poor. While it's important to promote competition and not enforce the idea that tourists are cash cows, remember that these people may be going hungry. So don't be too stingy and buy an extra t-shirt from someone or leave a tip for services well done.
Most internet cafes will have a computer with headphones attached. So if you have a Skype account, youíll be able to make cheap phone calls home.
Cotton clothing takes a long time to dry, in comparison to synthetic or wool. More over, if you are hiking in cold weather and your cotton clothing gets wet, it will feel cold the whole time itís drying up. On the other hand, a synthetic piece of clothing will warm up and feel warm even while itís wet. The other benefit of having synthetic clothing is that you can wash it in the evening and it dries up by morning.
I got this advice from a friend of mine and itís been one of the most valuable ideas to keep in mind. While everyone dishes around advice on how to better plan for travel (including this website), realize that the best part about travel are the unknowns. Itís far more fun to just go and figure stuff out on the fly without any planning. So letís leave it at that and just get out there!