There are some brilliant holidays these days. A young friend has just managed to book a last-minute one-week holiday in Barbados for under £300, all found. It's in a shared villa on the beach, and she is looking forward to spending most of the week soaking up the sun.

I was happy for her, but she's a patient, as well as a friend, and I didn't want her coming back ill. So here's how I advised her. It's advice that's appropriate for any holiday in a place that's sunnier and warmer than the British Isles.

The first priority is to look after your skin. That means no burning or tanning - they are signs of damage to the skin that you will regret later. Doctors in Britain, and especially in Scotland, have seen numbers of skin cancer cases rising steeply in the last 20 years, and the vast majority of cases have been caused by unwise exposure to the sun.

This advice is particularly important for young skin. A toddler or schoolchild that gets badly sunburnt - to the extent of blistering - just once has a higher-than-average risk of getting skin cancer later in life. But the people who really expose themselves to danger from the sun's rays are older teenagers and young adults - the people who spend the nights in the discos and the days asleep on the beach. It is repeated lying in the hot midday sun, day after day, for a week or fortnight every year, that damages the skin most. And using a sunbed in between times, to keep up your tan, makes the danger much worse. This advice applies to everyone, but is particularly appropriate if you are the fair, freckled type.

The Australians have taken the message on board. With a massive one in nine Australians developing skin cancer, the health authorities there have been preaching the need for wearing long-sleeved shirts and wide-brimmed hats, as well as sun-block creams, for years. And their cancer figures are beginning to fall.

So my first advice to my friend was to buy a big hat and take plenty of old shirts to wear on the beach and in the sea - you can easily get burnt through sea-water when swimming, even when you feel cool. And to put appropriate sunscreens and sunblocks on all exposed areas of skin whenever you go out. That means backs of ears and hands and the top of the feet, as well as the more usual places. People often forget their feet when they are wearing sandals or slip-ons. It is important, too, to protect areas of skin that have been scarred in the past or are freckled, as they are more vulnerable to pre-cancerous change than others when over-exposed to the sun.

In places like the Caribbean and the Mediterranean, remember that even the shortest exposure to the sun in the one or two hours around midday can harm you. It's best to take a siesta under a sun umbrella or even indoors at that time - the locals will certainly do that, and they have inherited skin that is far more resistant to sun-induced changes than yours.

If you do get burnt, it's vital to get cool and keep cool for a day or more. And to drink much more water than you think - several litres a day. Bottled mineral water is best in most resorts, not just because it is safer than the tap water in many places, but also because it replaces some of the salts you may have lost in your sweat. If you are so bad that you feel ill and are sick, get medical advice. Of course, you will have taken out health insurance before you set out.

One other thing - the summer in the Caribbean and in some parts of the Mediterranean is also the insect season. Your holiday can so easily be spoiled by bites from mosquitoes and sandflies, so take insect repellent with you, and put it on whenever you go out. Be meticulous about using the mosquito netting. It's not just that the bites can go badly septic, so that you may need antibiotics and be driven crazy by the pain and itch.

If you are going to the Tropics and subtropics you must know about the diseases these insects carry. They can range in different places from malaria to dengue and encephalitis.

So be prepared, enjoy your holiday, and come home healthy and happy

Converted for the new archive on 30 June 2000. Some images and formatting may have been lost in the conversion.