Travel and credit cards
Debit or credit cards are a useful way to access your cash and a good way of recording your expenses at a later date. It is inadvisable though to depend solely on your plastic in case they are lost of stolen.
Most places now take Visa, MasterCard, American Express etc. but for safety reasons you should try and pay in cash for most shopping and restaurants bills in case a copy of your card details is used when you are long gone.
Also watch out for bank charges when withdrawing money. It may be best to take out larger amounts with fewer withdrawals but be careful if you do this as you do not really want to be carrying large amounts of cash around either.