The ballroom dance dip is a charming and romantic move -- when it's done well. However, if you do not know how your hold your partner securely, she will at best refuse the dip and at worst fall down and drag you with her. Salsa, tango, and the Lindy Hop all incorporate dips, and if you know the proper form, your partner will feel safe giving you her weight and trusting you to help her elegantly lift herself up.
Raise your right hand from her waist to her upper-middle back. This tells her that you want to dip her. Apply a gentle pressure to her back, so she knows that you are ready to support her.
Glance behind your partner to ensure there is enough space for you to dip her.
Widen your stance so your feet are hip-width apart, and bring your right foot forward to support both of you. Lower her gently backward, keeping your spine straight and your back upright to counterbalance her.
Support your partner with the strength of your arm as she raises herself up with her abdominals. Press into the floor with your forward foot for extra stability.
Dips or turns are customary at the ends of songs. An experienced dance partner will mostly support herself in a dip, but a social dancer without training may rely on you to hold her up.
If your partner does not lean back into your hand when you signal her for the dip, she does not want to dip. Return your hand to her waist, and keep dancing.