I was reading a e-book called "penis of steel" and they gave some pretty good tips.
1. jack off and find your point of no return, thats the feeling u get when you know your about to come... now this takes practice but keep jacking off and remember the point of no return.
2. When you are jacking off and you get the point of no return feeling just completely stop and pull out, you can either think of something else or squeese your rod hard, when you are doing it with the girl... just stop and pull out and tell her to give you a second or use that as a excuse to change positions.
3. Dont think about it so much, in your head play a song and dance to it on beat. I personally play a song in my head, and talk dirty to her.
This is my 2 cents and it might not work for everyone, but it has helped me out a bit, so good luck