you can try varying the tempo, speeding things up winding you both up a bit and then as you get near the edge, slow everything right back down again :)

Masturbating do the trick for me. I ussually likes more the act in itself, than the brief eyaculation moment, so if I know that my partner is able to last for a long time, I masturbate even twice before an encounter.

You have to be careful though, because some girls likes to see and feel you come... even if you don't want to lol, so if your partner likes it go easy on yourself.

TEASEEE!
horrible for her (in a good way)

and makes you feel dominant,

basically extend the amount f foreplay

You don't have to make each individual act last longer if you do it 3 or 4 times per 'session' varying the positions as you go. Snuggle, do body worship, even chat while he gets his breath back and then hit him up again and again and again!