I think the best way to set a mood for a party is with candle light. Whenever I have a party I put tea lights everywhere! Like on the window sills, tables, basically anywhere in the house that it won't catch something or someone on fire. If you don't have any tea light holders just reuse clear glass jars from jams and sauces!
Tea light candles, box of 10 $2.95. Available at Cathedral.