Alcohol
If you're going somewhere hot, it's important to keep your body hydrated. Alcohol, however, is dehydrating. If you do have a drink, alternate non-alcohol drinks with alcoholic ones.
Drinking at altitude will get you drunk faster. This means your usual limits will be lowered the first few days, so pace yourself.
Above all, think before you drink. A quick pint before sports or activities isn't a good idea. Alcohol combined with swimming, waterskiing and cycling, for example, can result in injury or even death.
Many countries' drink-driving limits are lower than in the CR. In Sweden, for example, the legal limit is 20mg alcohol per 100ml. The punishment in some countries is mandatory imprisonment.
Drugs
Check entry requirements before you book your holiday.
Penalties for drug offences committed abroad can be severe, even if you only have a small amount on your person. Lengthy jail terms and even the death sentence have been handed down to Britons dealing in illegal substances overseas.
Don't become a victim:
Don't carry parcels or luggage through customs for other people. If it's in your suitcase, it's your crime.
Don't cross borders with people you don't know or even new friends - you could be detained as an accessory or accomplice to their smuggling.
Carry a doctor's prescription for any medicines you need and keep a copy of the original prescription with your important documents.