Before you make home improvements, consider the resale value

Some ''improvements'' can detract from the resale value of your home as much as others can add to it. In one recent deal, according to a real-estate broker here, the selling price of a house was at least $5,000 less than it should have been because the walls were painted a bright orange and the floors were carpeted in the same wild color.

Most buyers prefer neutral colors, although they may change them once they move in.

This is an extreme example, but it illustrates the point that equal home improvements aren't necessarily of equal value at resale time. And don't expect to recoup your entire investment for each improvement. Some can bring a 100 percent return, while others will net no more than 50 cents of the dollar, or less, in the best of times.

According to real-estate brokers, appraisers, and tax assessors, kitchen improvements bring the greatest return.

Additions like no-wax floors, modern appliances, pantry closets, and work islands all pay off in the long run, but only if they're properly installed. If they are poorly built do-it-yourself efforts using cheap materials that won't hold up, they can actually stand in the way of selling your house.

A modernized bathroom also will add value to your house. Replacing a standard sink with a vanity not only increases storage space, it also puts the plumbing out of sight. Adding glass or plastic shower doors is a good idea, too, and so is replacing gaudy color schemes with neutral-tinted tiles.

Both kitchens and bathrooms can be overimproved, however. Self-cleaning ovens are convenient, but they could turn off energy-conscious buyers. Washers and dryers are sometimes left in the house, so don't expect to recoup your investment on them, either. And flashy bathroom fixtures may suit your life style, but not that of others.

The rule of thumb in home improvements: Stick to the basics.

Adding an extra room, particularly a second bath, usually pays off. Family rooms, too, are important these days, as are third or fourth bedrooms. But five or six bedrooms will make your house harder to sell. And don't add a den or study if you already have a family room.

You may find needed space by enclosing a porch or deck or even refinishing an attic. Don't take the space from your garage, though. That's in demand, too.

Family rooms should be in the main living area of the house. Also, don't add a bedroom if the only access to it is through another bedroom. And don't make the mistake of combining two small rooms into one. That's a departure from the needs of most house buyers.

Some of the better investment improvements today involve energy. Adding insulation, storm windows, and a heat pump are doubly helpful because they not only save money for you by cutting your own energy costs, but they promise future savings for your buyer as well.

Fireplaces are another strong sales feature, but you won't get your investment back if you have to build a new chimney. Prefabricated, free-standing units are better. With glass screens, they're better yet.

You won't get all your money back with wall-to-wall carpeting either, unless it's practically brand new. Wallpaper, on the other hand, is a relatively inexpensive improvement that increases value so long as you stay away from strong patterns and colors.

One of the worst home improvements you can make, from the standpoint of added resale value, is to install a swimming pool or other luxury item such as a tennis court, greenhouse, or elaborate patio or deck. Many buyers see pools only as added work and expense, and perhaps a hazard if they have children. A tennis court or greenhouse is of value only to other tennis players or plant lovers.

There are also major differences of opinion on lavish landscaping. To you, it may look terrific and be no trouble at all. To a potential buyer, however, it could mean added yard work. For optimum appeal, it is better to keep your lawn well groomed and a normal amount of shrubs and plants properly trimmed.

When establishing value, tax assessors usually figure that adding space will return anywhere from 60 to 100 percent on investment. This ranges from a low of 60 to a high of 100 percent on new kitchens and two-car garages and 75 to 100 percent on bedroom additions.

Modernizing, they figure, pays back only 30 to 55 cents on the dollar: 30 cents for converting a basement to a recreation room or a garage to a family room, 30 to 50 cents for adding an attic bedroom, and 45 to 55 cents for improving a bathroom.

When tackling a home-improvement project, it is usually best to leave the work to professionals, including, often, an architect or interior designer. A do-it-yourself job that is poorly done detracts from, rather than adds to, the value of the home.

There is no rule of thumb on how many improvements you should make. But even if your pocketbook can handle a big job, you probably shouldn't do more than one improvement at a time.

And you should always keep in mind that the changes must not only be compatible with the rest of the house, but they should fit in with the neighborhood too.

A new wing could send the value of your house up past the value of other houses in your area. If yours is a $50,000 home surrounded by $70,000 houses, $ 20,000 worth of improvements may pay off. But if the other houses are worth the same as yours, you're overimproving.

One builder in the Washington area added a swimming pool to his residence. The kidney-shaped pool with a big ''H'' on the bottom, plus a pool house, shower room, equipment room, and extensive landscaping, cost $25,000. Yet the market value of the pool is only about $10,000. Even in a higher-priced locale, the most he could hope to get back on his investment would be $15,000.

Speaking of neighborhoods, it is worth noting that the ''improvements'' your neighbor makes - for better or worse - can affect the value of your house. Take the man who celebrated the bicentennial in 1976 by painting his house red, white , and blue.

Tax assessors cut the value of the house next door by $14,000.