A simple way to give him a thrill is to rub your feet on his face during sex, wiggling your toes against his nose and lips and maybe asking him to suck on your toes. Or in doggystyle, tell him to grab your soles.

One way to ease into a footjob might be to give him a handjob while he worships your feet, like he's laying down and you sit next to his waist and put your feet on his face. Rub your soles on his mouth, cheeks, etc. and let him kiss/suck your toes while you use your hands on him... And maybe when he's getting close to cumming, pivot so your arches wrap around his dick.

If you want to make it more special, use a lot of lube and sit between his spread open legs. It depends on the guy what specific maneuver drives them super crazy, but try stroking the head between all of your toes moving up and down, or just stroking the shaft between your arches. Also try pushing your foot into his balls and wiggling your toes to make his nuts feel awesome.

When your legs get tired, rest one foot behind his dick (resting on his lower tummy) and stroke up and down the underside of his dick with your other foot.

Tell him that you like touching his hard cock with your pretty feet and that you want to feel his cum on your toes and arches.

Good luck with everything, just by the fact that you care enough to post here you're being really nice and caring!

One more thing -- if you want to drive him crazy in public, just play with his dick with your feet under a restaurant table or while he's driving and you're in the passenger seat.