Take two photocopies of your passport before your holiday. Leave one with a relative or friend and take the other with you - keep it in a separate place to your actual passport.
Keep your passport with you whilst you're travelling. Keep it in your hand luggage or in a zipped pocket. Make sure you're ready to produce it promptly when required.
Be wary if you're ever asked to surrender your passport. While some foreign officials may ask for your passport (as may some hotels) check with your travel operator or the British consulate as to whether this is standard procedure or not.
If your passport's stolen or lost while you're away, report it to the local police immediately. Then get in touch with the nearest British consulate or embassy for further advice. The British Consul can issue an emergency passport if necessary.

If you're changing cash before you go: Shop around to see who's offering the best exchange rates and commission. Make sure you check on the total cost of the transaction though - you may find that an attractive exchange rate is offset by higher commission charges...
You can order foreign currency via ladsholiday.com with our partnerTravelex- they'll provide the best rates - guaranteed. And they can deliver the money to you or you can collect it at the airport.
Other options in include the Post Office or Marks and Spencer neither of whom charge commission and generally offer a good rate. And remember that most banks and bureaux de change will only exchange notes - not coins - back into sterling.