As a superblaster, here's my opinion. First off, there are just some people who shoot, and others that dribble, just as some have big schlongs and some small. That said, go to threads on increasing the size of your ejaculate. There are supplements that will help a little. Also, do kegel exercises daily to improve your squeezing mechanism.
Then, if you want to spray your semen all over the place like me, jack off three times a day for three days, then wait 2-3 days. Drink lots of water (and not just before you want to ejaculate) as staying hydrated will help your semen stay more liquified and less jellylike. Finally, find out the jack style that will work for you. If you watch all the porn that's out there, there is some technique involved and everyone has a different style to bring out that explosive load.
If none of this helps you, take solace in the fact that most of the women I've known don't care for the BIG WAD. It's messy. True there are a few that truly love to have their body coated with your big load, but most don't(in my experience). Good luck and Happy Blast off!