Try 'demo' skis before investing in your own

You don't have to buy expensive equipment to go skiing today. More and more people - some of them experienced skiers - are renting and leasing skis. We'll talk about those options in a future column. But if you are considering new skis this winter and are still not sure what to buy, this is the time to act.

For the next two or three weekends ski manufacturer representatives will be busy visiting ski areas in various parts of the country. ''Demo days'' have already been held at several ski areas with early openings, including Waterville Valley, N.H., Stowe, Vt. and Sunday River, Maine.

This coming weekend (Dec. 5-6) Wildcat, N.H., Jiminy Peak in the Massachusetts Berkshires, and Indianhead, Mich., are among the areas where skiers can try out the latest skis of most major manufacturers without paying a cent. The following weekend (Dec. 12-13), skiers can do the same thing at Sugarloaf, Maine, to name only one area. And additional ''demo days'' will be held at some of these resorts as well as many others throughout the winter.

By taking advantage of a ''demo day,'' you can try several different kinds of skis under relatively controlled conditions. Snow conditions and runs should be the same for each pair tested. Ski them easy; ski them hard. Try them over the bumps and then go cruising. It's just about the best way to find out which skis go well with your kind of skiing. And you can do it all without paying anything for the privilege.

Just remember that the demonstration models you ski on are apt to be the best-tuned pairs you'll ski on all winter. That alone will positively affect your skiing. Also remember to try only new skis, never new boots and skis at the same time. Otherwise you'll have no frame of reference for comparison with what you have been skiing on.