Depends on how well you know her, and what kind of a kiss. If it is an innocent kiss, then perhaps on her shoulders, or one on her shoulder one on her arm. If it is a more intimate kiss (open mouth), then to her your hands on her hips is nice, or one arm around her waist and the other on her hip.
you lost your hands? have you checked your pockets?
on her upper arms or holding her hands in yours and on her hips if you both feel comfortable with that.