my two bits
a) some say masterbating before sex, makes you last longer when you have sex, the only problem is, you lose some of the desire to actually have it, and some guys get really tired after ejaculating, so that can cause problems. Depends on the person. I myself have not heard of the masterbating AFTER sex to lengthen the next time...
b) there is a technique of certain sexual arts.. of being able to control the muscle that will allow your ejaculate to come out... its the same muscle that you use when you stop the flow of urine coming out, while urinating-- like stopping it half way. It says if you practice using this muscle, (there are several exercises you can do to strengthen it, look it up online), that you can, when you are about to ejaculate, that you use the same muscle you use to stop the flow of urine, so that you have the pleasure of an orgasm, without actually, ejaculating. Which in turn keeps you erect, and allows you to continue having sex and theoretically having an orgasm more than once in one 'go'.
Now to be honest, I have no clue if this technique actually works. I have a friend who swears by it, But its worth a shot if you are really interested? I believe you can find the technique online, if not its also a tantra used technique I believe.
Also lasting longer is not always a sure fire way to be a better lover.
Try reading up on kama sutra, or the tantric arts. They give alot of, how to be a better lover stuff emotionaly and physically.
Also.. there is a technique my brother taught me.. its a little strange...
basically when you feel yourself leading up to that point of no return, you simply start thinking of... baseball statistics... or whatever sport you want. Seriously I know this sounds messed up, but I tried it, and by doing math and working out batting averages, etc-- and then focusing on sex, then baseball, then sex, you can stay hard and not ejaculate for longer than your normally would... try it with yourself masterbating and see if it works for you. Its not the nicest of ones... but if you're looking to impress, it might work?
and another one--is using certain types of condoms... made for.. a.. 'sensitive' guy. IE someone who ejaculates faster than they'd like, of course you get reduced sensation as the trade off.
good luck to you.
edit-->P.S. the Sport one might not work for you if you are somehow aroused by the sport or by doing math