@harmonica,
I am not going to teach you because your suppose to discover things on your own.
1. The penis edges, balls and skin is sensitive in many ways like the chest pecks/nipples.
2. Manhandling her might actually do something for you.
3. A little nibbling, some ice, or even going for the edges of the balls might also do the trick as well.
4. She could put more effort into it via her head movement via your "head"
...... I know