Philadelphia-based DJ Diamond Kuts says it's important to choose music that makes you feel good, but jerky stops and starts between songs with different tempos can make you look like an amateur. To premix tunes before the party, we like the iDJ app
($1.99). As you create your playlist, this application automatically matches the beats of different songs and adds transitions for a seamless flow of music that keeps everyone on the dance floor. Start with a line dance song, like "Electric Boogie" (better known as "The Electric Slide"), where everyone already knows the moves (or can easily follow along) to get your guests on their feet, says Kuts, who was just selected as one of Dove's Go Fresh DJs
. If you've got a mixed crowd, stick to feel-good classics, she adds, like Marvin Gaye, Stevie Wonder and Michael Jackson. Or opt for her favorite summer anthem of 2011, "Last Friday Night," by Katy Perry. Want to call it a night, but the party is still raging? "Play two slow songs back to back," says Kuts. If that doesn't work, she relies on the no-fail announcement known by good DJs worldwide: "You don't have to go home, but you have to get the heck out of here!"