There's a whole bunch of stuff you could try. But smiling's good!
These are some of the things which women frequently do that work on me:
1) Be girly!
2) Confident focused eye contact
with smile
3) Beat him at the eye contact game!
4) Try brushing into him as you pass him; or making brief and sporadic physical contact when you sit next to him (but don't go over the top!)
5) Try crossing your legs and lifting your feet up and down in a speedy manner, twisting at the same time!
6) Step in front of him close with your back turned.
7) Chew gum and play with it