Your college roommate calls. She wants to get away from Tulsa and come visit for a few days.

So you put fresh sheets on the extra bed, place a stack of towels in the bathroom and arrange a big bouquet of flowers for the dresser. You purge your refrigerator of half-empty mustard jars, soured jellies and flat club soda and load up on real food. That's the easy part.

Now, you wait for her to arrive and tell you what sights she has been dreaming of seeing in Washington. The Washington Monument. The Air and Space Museum. The FBI tour. The "quaint little village" of Georgetown on a Saturday afternoon.

Without being rude or tacky, there is a way to gracefully bow out of playing tour guide. The solution lies in being creative about suggesting to guests that they go off and explore the city themselves and in stocking some appropriate tools to help visitors figure out what they most would like to see and how to get there.

"When friends call and say they want to come visit, I say, 'Please come, but don't expect me to take you around the capital. I run my own business, I just can't do it,' " says Rochelle Jaffe of Travel Books Unlimited in Bethesda, who keeps a shelf of Washington guide books in her guest room.

Whether you want to set aside a small stack of books, or fill a basket with guidebooks, subway farecards and a spare foldable umbrella, any effort you make will help people feel at home and comfortable in making their way around. Recently, some new sources for Washington touring tips have been published, including walking tours of the city on cassette tape, and some guidebooks with new twists on seeing the city on foot or by Metro.

Among suggestions from some of these new works as well as from old standbys recommended by local travel bookstore owners:

Tapewalks. Local businesswomen Barbara Tempchin and Judy Zickler have produced a series of informative, witty walking tours on cassette tapes. Currently they are offering tours of four different areas of the city: Georgetown around Georgetown University; The Dumbarton Oaks section of Georgetown; Embassy Row and Dupont Circle; and a stroll around the White House. The tours are lively and full of anecdotes and interesting tidbits on the social history of Washington. They also point out nearby bistros where it is possible to have a light lunch or a cold drink during the tour. The tapes are about 45 minutes long and cover about 1 1/2 to 2 hours of walking time. Small maps are included. They are available for $11.95 each at Olsson's Dupont Circle and Georgetown and The Phillips Collection Museum Shop.

Washington D.C. Sightseers' Guide by Anthony S. Pitch. Ideal for first-time visitors to Washington, this pocket-size guide is handy because it has a map on the back cover locating attractions from the Senate Office Buildings to Woodward & Lothrop. The guide covers all the major sights and some offbeat ones and has listings of major embassies and other useful phone numbers. Each attraction is listed with directions on how to arrive by Metro or Tourmobile. Available for $3.95 at most major bookstores.

Station Master's A Pocket Guide to Metrorail Station Neighborhoods. This book helps visitors wade through Metro's maze and also answers the two questions that must immediately come to mind when a tourist gets off the escalator at a strange Metro station: "Where am I and what do I do now?" Author Larry Bowring, a cartographer, has filled the tiny book with clear and concise maps, good instructions on that complicated procedure of purchasing a farecard and a thorough index. The guide, $3.50, is available at The Map Store, 1636 I St. NW, and at local drug and grocery stores.

A Museum Guide to Washington, D.C. by Betty Ross. Written by an experienced travel writer, this book is ideal for those art-lovers who come to Washington eager to see as much of the art, architecture and decorative arts that this city has to offer. Available for $9.95 at Travel Merchandise Mart, 1425 K St. NW and Crystal City; The Map Store; and other Washington bookstores.

Washington Itself by E.J. Applewhite. A personal view of the city focusing on the varied sights in different neighborhoods, including their architecture, churches, historic homes, parks and museums. It includes an easy-to-read and informative narrative that will be of interest to both tourists and natives. $8.95. Available at Travel Books Unlimited in Bethesda and other bookstores.

Natural Washington by Bill and Phyllis Thomas. When outdoor-lovers come to visit and they tire of the monument routine, pull out this handy and concise little book that lists little-known places around town to jog, bike, see flowers, hike, picnic or just relax. The whole metropolitan Washington area is included. Available at Travel Books Unlimited and other bookshops for $9.95.

Washington map placemat. For visitors who are slow in getting the hint, use these wipe-clean placemats at breakfast to encourage independent touring. The mat features a Metro map on one side and a map of the Beltway on the other. The $2.95 mat is available at The City Shop, Pavilion at the Old Post Office, 1100 Pennsylvania Ave. NW.