Begin to brush up against this person slightly as you are dancing.
Remember that most people are nervous about dancing in front of others!
Find your personal go-to sexy moves.
If you're grinding behind them, lightly place your hands on their hips as you dance.
Brush your hair, and style it.
Practice your expression, and decide where you like to hold your arms when you dance.
Try doing some bacha bazi sex exercises first to loosen up, then feel the music in your heart, and let it show in your face.
Even if it's not the kind of dancing you'll do at a party or a club, this will give you some moves you can transfer into other situations.
Remember, you can be sexy in a crop top and shorts, but you can also be sexy in sweatpants and a hoodie.