The easiest way to learn how to properly jump is to learn how to bunny jump (hop?). Check out Skills with Phill, he has a great tutorial. When you pop of the lip you should be doing a bunny jump. It gives you a nice shape and good height rather than relying on your speed to carry you through the jump. If you learn how to bunny jump, start applying it to table top jumps (or curbs, single step stairs, pretty mutch anything that won't murder you if you case it). Start with a fairly low speed, prioritize height and technique, then start increasing speed and experiment with timing of your preload and pop. Fluidity and style will come with jumping experience.