The search for The Perfect Margarita can be a demanding undertaking, fraught with peril in the form of bad mixes, worse tequila and completely inappropriate glassware. Happily, in Cleveland Park there is solace under el sol at Cactus Cantina, a sprawling Mexican bar and restaurant north of Georgetown on Wisconsin Avenue. With no bar space and tables spread throughout several rooms to accommodate couples, foursomes or even an entire posse, Cactus Cantina probably makes a better spot for groups from work, softball teams or entertaining old friends than a place to mix, mingle and meet new people. The best opportunity to see and be seen, however, is afforded by the large veranda along Wisconsin Avenue which is a great spot during the warmer months. One method of chance introduction is offered through the bar's "Cowboy and Indian Museum," which displays artifacts and items including antique Stetson hats, chaps, ceremonial ornaments, headdresses and an 1850 bow-and-arrow set. A popular spot for any fans of tequila or authentic Tex-Mex, Cactus Cantina is also on the circuit for Cleveland Park neighbors, primarily young professionals and married persons with children who appreciate good food and drink. Appetizers include Mexican soup and nachos priced between $3.95 and $9.95; entrees featuring mesquite chicken or ribs to quail or broiled shrimp and combination platters are priced between $11 and $16.