Practise very slowly in the mirror and break it down, work on lots of discipline and patiance to get it right.
Guys saying you dont turn your hip are absoulutley wrong, it is of utmost importance your turn your hip and lock out your jab to make it a good solid scoring shot.
Correctimundo, but that being said, there are lots of jabs, some of which u dont turn hips and arent stepped into. The turning of the hip though and lockin out the jab will not only score u points with the jab, but that cranks all of the weight onto the back leg which sets a a huge straight opportunity for you.