Scientifically speaking, certain critical switches must be triggered before your partner's brain orders the release of vasoactive intestinal peptide, the chemical that increases blood flow to the pelvic area, swelling her inner and outer labia and causing her to feel the gnawing tension of sexual desire. Though the intricacies of brain chemistry may be difficult to grasp without a medical degree, there are still plenty of easy, everyday things you can do to get the requisite juices flowing. There are two overarching components to turning your partner on. The first is to start outside of the bedroom.