Well, I think there are very many docs on a subject of "How to last longer in sex?".
It also is referred to as "How to avoid premature ejaculation?" or "What is a female orgasm?" :).

What I want to say, that sex is a lot of psychology and inner things than technics or tips and tricks. Which means that there are just some things to understand, rather than to learn to do. And ejaculation, too, belongs here :).

Firstly, recommended is try to forget that you ever will be coming at all.
Just enjoy this very second, making it last as long as you can.

That's about overall process. Just think of it :).

Next, remember girls can be pleased without using your dick at all :).
Which means, if you ever suddenly recall you can come, and you feel as you can soon, but you see your girl's not ready yet, then try the following.

Stick it out of her, and.. well, we're all different, but do what you would have done if you did not know how to have sex. Stroke, kiss, tease, caress..
Once again, forget about your dick).

Then just keep doing it :).

Maybe this seems a bit incomplete and selective, but that's what coming to mind.
If you know anymore on this, feel free :).