With interest rates at vertiginous heights, many homeowners who thought they had brought "starter" homes are concluding that, with some work, they can stay where they are indefinitely.

One firm that has decided to get in on the do-it-yourself market is United States Gypsum. To get the message across they have sent a representative, Marion Wear identified by the company as Ms. Fix-It -- to eight cities to discuss the projects that homeowners and specifically women can undertake.

Wear estimates that more than 100 million do-it-yourself projects were completed in 1979. And, she says more than 60 million of these were done by women.

"The fear of trying is the greatest obstacle to doing it yourself," Wear said on her stop in Washington. To allay that fear, Wears encourages potential do-it-yourselfers to take advantage of available information: Materials for projects are specifically packaged for inexperienced workers; plenty of literature is available free at home centers and supply stores. Libraries have sections on do-it-yourself work, and there are kits for almost anything, including homebuilding.

Wear said she and her husband did their own painting and wallpapering, removed walls and put up drywall, hung shutters and changed the bathroom fixtures in their home near Chicago. They also added electrical outlets and extended a gas line.

"It's not as overwhelming as it sounds," she said. "It just depends on the individual."

She urges inexperienced workers not to rush into a project. Instead, they should take it step by step:

* Talk to family members and study traffic patterns within the house.

* If its a major project, check building-code requirements.

* Draw an accurate floor plan of the area to be remodeled. The standard scale is one inch to one of foot.

* Make a list of materials. If you aren't sure of what you will need check in libraries, talk to friends, ask advice at hardware and home center stores. Look for remodeling brochures and booklets.

* Always buy the best materials and tools you can afford. Projects are easier with the right equipment.

* Make a budget for the project but leave some leeway -- as much as one-third more -- for the unexpected. Structural defects can be found along the way, or if the plaster is removed from a wall you may decide to insulate while you have the opportunity.

* If there is a tool you will only use once, try to borrow or rent it.

* Don't set a rigid timetable unless you have done the job before. You will only get frustrated.

* Try out a new skill in an less obvious place first so if you make mistakes they won't be seen.

Wear also has some advice for those selecting a house to buy. Since prices are so high, many people are settling for less than they want, figuring they can improve it. That is fine, she says unless the improvements on the house will make the resale value too high for the neighborhood. Of course if the buyers plan to stay in the house, the sale price is not a consideration.

A house should be selected on the basis of what projects the buyer is willing and competent to do, Wear said. Someone without much experience or skill should buy a house that needs cosmetic work, such as replacing or cracked plaster, painting or wallpapering, and leave the structural changes for someone more skilled. Buyers also must decide whether they can live in the house while they work on it.

Wear also has ideas for apartment dwellers. The first rule is, of course, to check with with the landlord to see what is permissible under the lease. There are now available wallpapers than can be stripped easily so the landlord may allow renters to put some up or take down the existing paper. Or he may allow leasees to paint over the wallpaper.

For less ambitious tenants, cosmetic work can be done on a dated bathroom by using modern shower rods or replacing the shower door. Extra storage space can be created by putting up peg boards. Wear says the look of a room can be changed by adding vinyl molding, which will not break and comes in various colors and wood finishes.

When it comes to major remodeling projects, United States Gypsm figures show Americans spends most of their remodeling money in refurbishing their kitchens. A new kitchen and new bathrooms add more value to your home than any other remodeling projects, Wear says. For the fortunate ones who can go in for such major projects, Wear has some suggestions on dealing with a contractor.

* The best way to find a reliable contractor is through a referral from a friend who has had similar work done. If that doesn's work, ask at the home center or building supply yard where you buy your materials.

* Get three bids and be sure to provide each contractor with the same specifications. If one bid is much higher or much lower than the others, ask why. The lowest bid is not necessarily going to be the best choice because the workmanship may not be as good as someone who will put more time into the job.

* Always get estimates and specifications, etc. in writing.

* Most important of all, Wear says, is "feel free to ask questions." The final product will depend on your ability to communicate with the contractor.