As mentioned in the last post.. throw more jabs.

I'm pretty much a beginner myself and it may sound dumb, but it's true, you want a good jab.. keep jabbing.

My advice would be to shadow box very slowly focusing on proper technique, posture, balance, form, etc. Then as you start to feel that all that is in place speed up. If you feel that speeding up is throwing something off, slow it down a notch and slowly work your way up.

Another thing is continuously jab at the heavy bag. Again focusing on technique, etc. Then do the same with the double end bag.

Once you feel that your jab is getting better, get a partner and go a few rounds sparring with just the jab. It'll help you look for openings, teach you to use feints and all that good stuff. It'll also start building a foundation for reading your opponent and defensive techniques and maneuvers.

Always keep the following in mind; Jab is not about power, and Speed means nothing without technique.

oh and also, watch and understand the following videos...