WASHINGTON — Since writing about vacation time-shares, I've received quite a bit of mail from time-share owners — many of them unhappy that they can't sell them — and others with good advice for newcomers to the time-share market.

Time-share ownership can be worthwhile, but it can also be very frustrating. Just take a look at some comments and questions from readers, along with my responses:

John Bredstrand from Vancouver, Wash., said: "You mentioned that a time-share should not be looked at as an investment. That is an understatement. You are very likely to be very disappointed if you try to resell a time-share with the idea of recovering even half of your investment. For the purpose of time-share research, a great resource is the Timeshare Users Group at www.tug2.net. This is a topic I think the public should definitely be informed about."

And I definitely agree. I also concur that the volunteer-run Timeshare Users Group (TUG) is a useful Web site for potential time-share owners, current owners, and those interested in selling their time-shares. Most of the information provided by the organization comes from time-share owners. TUG collects reviews and ratings on more than 2,000 time-share resorts. I suggest if you're interested in buying a time-share, visit this Web site first.

It will cost you $15 for the first year of membership. The fee pays the expenses of running the Web site. For your money, you get access to the part of the site that provides the resort reviews and ratings. The reviews include pictures of the resorts, general resort information and a list of e-mail addresses of owners willing to answer questions. Members also are able to list their time-share for sale ($10 for a four-line ad).

If you want general information and advice about the time-share industry, you don't have to become a member. That information is free. Look for the heading "Timeshare News /Info." There you will find articles on time-share scams along with tips on buying and selling.

Colleen Lohnes from Morrison, Colo., asked in an e-mail: "I wonder if you have any ideas in the area of time-share resales? My experience has probably been typical and very frustrating and disappointing. The promises of the companies that say they can rent or sell your time-shares are overinflated and I wonder if they even try ... or they do very little. Unfortunately, I paid almost $1,000 to two companies. Despite regular calls, they have never rented or sold either of the two time-shares we placed with them. Any suggestions that don't require up-front payments?"

As this reader found out, selling a time-share can be very difficult. Here again, TUG has some great information. First, the group says you should never pay an up-front fee as a condition to buy, sell or rent your time-share. Time-share owners desperate to sell often fall victim to time-share resale scams. TUG recommends that owners deal only with a licensed broker/agent who works on commission from proceeds of a sale.

It's important to note that time-shares sell for 30 percent to 50 percent of what was originally paid (and that's if you're fortunate. Some owners can't give them away. You might do better on the resale market if you own a time-share at a premium, brand-name resort developed by such companies as Starwood Hotels & Resorts, Disney, Marriott, Hilton and Hyatt.

Certainly you can try to sell your time-share yourself on any number of online auction sites, such as eBay. Also contact the developer to see if the company has a resale program, many of the brand-name time-share sellers do.

Also when selling, keep in mind that even if you don't get much for your time-share, you could be freeing yourself from annual maintenance and exchange fees. In some cases that can amount to more than a $1,000 a year.

One time-share owner, who asked that he not be identified, wanted to re-emphasize those high costs. He wrote: "Annual maintenance fees plus exchange fees, plus exchange company membership fees ... add up quickly, so that it is often as cheap to rent as to (buy) a time-share."

If you don't want to go the do-it-yourself route to sell your time-share, try Timeshare Resales Worldwide (www.all timeshare.com), which specializes in resales of vacation time-share ownership.