SFO -> Brazil

Some countries requires that your passport has at least 6 months validity left.

Reconfirm your flights as there may be airline schedule changes. Your return flight must be reconfirmed at your destination directly with the airline 3 days prior to your departure.

Remember to keep a close eye on the passport copy - it's a great asset if you lose the original, but can also be used to steal your identity if it gets into the wrong hands.
If you have a web based e-mail platform, e-mailing yourself scans/copies of important documents and passport info is a great alternative to hard-copies. It's easier to access, less likely to be stolen, and guaranteed to always be on hand.

Memorize PIN codes to credit cards so that you can use them with ATM machines to get cash.

Where pickpockets are a problem, carry your wallet in your front trousers pocket.

Take a pair with pockets - doubles as a swimsuit for men.

Also handy for pulling out splinters

If you require prescription lenses in your glasses, take a spare pair of glasses with you. There is nothing worse than having your glasses break or losing them on holiday and having no spare pair to fall back on.

For international travel: consider unlocking your cell phone SIM card so you can use your phone there (purchase a local SIM in your destination).