There's nothing wrong, of course, with putting out the tonic, the half-gallon bottles, turning down the stereo, ordering the canapes and leaving the door ajar. A good guest list will guarantee the mix, the chatting the night away, the making of new friends and perhaps some enemies. But there is also the matter of doing something memorable, something beyond what can be eaten, drunk and looked at. There is live music.

Not you at the Steinway singing Camp Keuwaden songs. The real thing -- memorable, professional. Rental music. Besides, your friends are probably doing it already. An increasing number of Washingtonians are hiring live music to jazz up parties in their homes and there are a growing number of music groups for hire. All you need is a good idea.

There was, for example, a Washington woman who invited the entire family to celebrate her parents' 50th wedding anniversary. She hired a barbership quartet to sing and held the party in the home in which her parents were married.

Or the people who decided the appropriate going away party for a co-worker returning to Texas was a country and western bash. Everyone dressed in cowpoke clothes and danced to the music of a four-piece country and western band.

Or the young man in Alexandria who planned a romantic dinner at home to propose to his love. He hired a violinist to serenade while he placed the ring on her finger.

Imaginative occasions such as those unfortunately require a bit of thoughtful planning to avoid last-minute panic. And there are some details you ought to know:

Musicians usually need at least a month's notice. At holiday times, plan for two to three months' notice.

A romantic evening with soft music and dimmed lights requires a different group altogether from an evening filled with excitement and a rhythm and blues band.

Think space. A living room or family room that will comfortably handle 20 to 30 guests will only call for one to two musicians. On the otherhand, if your home is larger and you want to invite 100 guests, hire a small band or ensemble.

Warn the neighbors, especially if you plan to boogie outdoors.

Sit-down dinners, light buffets and wine-and-cheese menus each call for different groups that may play at different times. Or you might be able to arrange for a diversified combo that could offer classical music while guests arrive and chat, blues while they dine and something upbeat later.

The size of your guest list may dictate how many musicians, but the bills in your briefcase will tell you which group you can hire and how long they can perform. Fees cover a lot of checkbook variety. A musician just starting out may be willing to perform for $25 or $50 for an evening. But you could pay as high as $200 or $300 an hour for a larger, more experienced or union-affiliated group. There may be some price flexibility, especially if the group can schedule another preformance around yours.

Most musicians have a minimum, often two or three hours, and some have contracts and require deposits. Try to see the group perform before you hire. c

Once you've agreed on a particular ensemble, give them as much information as possible before they arrive. Tell them what you want them to wear and any special requests you may want them to play. Know in advance where you want them to perform and if there will be room for dancing. Find out how much breaks they intend to take. And be certain they have rehearsed together before they arrive at your home.

This summer Sandra and Bernard Renzy of McLean gave a coming-out party for their 18-year-old daughter Dawn. It was a special occasion, and they wanted to do something different.

The Renzys decided on a party with a jazz theme and started their search for a live band. The party would be held outdoors on a large lawn that could accommodate the 100 or so young people who would attend. They also planned to rent a portable dance floor.

"But the most difficult task was finding the musicians," said Sandra. "I called the Goose Creek Jass and Ragtime Society. I had heard several of the Society's jazz bands perform at a party in Middleburg, and thought they were quite good. But the prices I was quoted were a little too steep."

So she called a friend who is a jazz enthusiast. Her friend recommended the Federal Jazz Commission, a Dixieland jazz band. Their price would be $300 for three hours and their references were good.

"I then called the managers of local restaurants that featured live jazz music and asked for referrals," Sandra said. "The final step in our search was to have Dawn and a friend listen to some of these bands in the clubs and restaurants where they were entertaining. The Federal Jazz Commission was again among the bands we checked, and Dawn chose these musicians for her party."

If you don't have time to conduct such a thorough search, try these sources:

Local music schools and university music departments for referals to students and teachers.

Local cultural organizations, associations, churches, and embassies.

City, county or community recreation and arts departments for musicians who may have performed recently.

Disc jockeys or hosts of local radio and TV programs.

Newspaper classified ads under the heading "musicians available."

The D.C. Federation of Musicians (244-8833) will send you a list of contractors and orchestra leaders.

The Folklore Society of Greater Washington refers callers to local folk musicians (281-2228) and ethnic musicians (573-1315).

The D.C. Youth Orchestra Program (723-1612) provides musicians for many parties. Payment is in the form of a donation to the program to cover expenses.

The Washington Performing Arts Society (393-3600) sends callers a list of musicians in their "Concert in Schools" series.

The John F. Kennedy Center for the Performing Arts refers callers to the music management firm, Elliot Siegel Music Management (966-0003).

Finding musicians is sometimes easy, but it can be very risky," says Leah Johnson of Dumbarton Productions, a Washington clearinghouse for musicians. "And it can be a great deal of work. A music contractor or booking agent can save people time and worry, and the musicians don't necessarily cost more."

Contractors know many musicians in the Washington area and have screened them. If a client wants to hire a chamber ensemble or a brass band or a rock band, they check their files and find the musicians available for those dates. They will quote each group's prices and help choose the one best suited for a party. "We function as a quality control agent for our clients," says Johnson. "In fact, we guarantee that if for some unforseen reason a musician can't play for a party, we find another to take his place, or, if necessary, we'll find another group. So there's nothing for the party giver to worry about."

Two months ago Sandra Grice and Stephen Glassman held a picnic for 250 people and their children at their farm in Laytonsville, Md. They collect antique clothing and furniture and their farmhouse dates back to 1852. For them, it had to be an 1890s picnic complete with a hot-air balloon, an old-fashioned ice cream fountain and a cotton candy machine. Their friends dressed for the Gay Nineties.

The musicians -- a barbershop quartet and a five-piece brass band -- alternated for four hours while strolling throughout the party grounds. bThe total price for music was $400 and the musicians were hired through Dumbarton Productions.

When planning the picnic, Sandra Grice called Dumbarton for help. "We had heard a string quartet from a local high school performing in Georgetown. We spoke to the musicians about playing for our party," she said, "but they couldn't commit themselves to our date. Many were not sure of their school schedules and the 50-mile round trip to our home seemed a little too far for them to travel.

"When I added together the time I was spending looking for a group on my own plus the small difference in cost between what these high school students were going to charge and what it would cost through Dumbarton Productions, it was an easy choice." And one she says she would repeat again. They plan to have a party keyed to a different era next year.

There are music contractors to fit every party giver's needs. Below is a list of just a few of the area's many.

Gene Donati Presentations, 4201 Connecticut Ave. NW. 667-6318.

Elliot Siegel Music Management, 3303 Van Ness St. NW. 936-0003.

Jack Morton Productions, 1825 K St. NW. 466-2900.

Sidney's Orchestras, Mayflower Hotel. 783-2777.

Howard Devron Orchestras, 3428 N. Edison St., Arlington. 538-6110.

Hill Herwood's Music, 8422 Georgia Ave., Silver Spring. 587-7779.

Lee Maxfield, 3933 Benton St. NW. 337-1414.

Bluegrass Country Booking Agency, 1137 N. Highland, Arlington. 528-7012.

Words and Music, 8600 Milford Ave., Silver Spring. 588-6119. Features Dixieland jazz, swing and ragtime musicians.

Strolling Strings Associates, 13221 Piscataway Dr., Ft. Washington. 292-2929. Features violinists, bagpipe players, banjo players, bassists, cellists and accordionists.

The Society for the Preservation and Encouragement of Barbershop Quartet Singing in America. Call the local chapter nearest you. Alexandria -- 938-3001. Anne Arundel County -- 301/761-0545. Arlington -- 521-0207. Bowie -- 262-4533. Columbia -- 301/730-0561. Washington -- 450-5996. Fairfax -- 573-2061. Frederick -- 301/271-7150. Manassas -- 703/754-8288. Montgomery County -- 251-0920. Prince George's County -- 735-4843.

The Sweet Adelines -- women's barbershop quartet. Call the local chapter nearest you. Alexandria -- 360-3225. Annapolis -- 301/721-2677. Arlington -- 243-6363. Manassas -- 703/361-7077. Montgomery County -- 649-6201. New Carrollton -- 474-1108. Springfield -- 971-7414. Vienna Falls -- 703/494-3547. Wardorf -- 853-2891.

Davis Deejays for Dances, 1005 Paddington Pl., Annapolis. 251-1777. Provides fessional DJs, sound systems and records of your choice.

Amusements Unlimited, by appointment at 4108 Howard Ave., Kensington. 593-0538. Rents juke boxes and records of your choice.