this is a great video on wake jumps, check it out.
http://www.youtube.com/watch?v=Ckkf840HZE4
a thing i will add is to try hard to keep both hands on the handle. don't let a bad habit form from letting go with your back hand every time.
Try to jump just a little higher and/or farther toeside too. might as well work that side too. sometimes people will feel something kind of click jumpi9ng toeside and can use that heelside... i know i was that way.
a metaphor to expound on what Clay said: Getting pop is similar to jumping on a trampoline. a trampoline has give and so does the surface of the water, but more mushy in comparison to a trampoline. one actually doesn't "jump" on a trampoline, to do so wouldn't get you far off the mat. getting air on a trampoline requires a person to extend their legs (standing tall) at just the right moment to rebound off the trampoline returning to its shape. getting pop off the water is kinda similar. as you edge into the wake it is comparable to pushing into the mat of a trampoline.
sometimes a rebounding ollie jump after an ollie can be effective in feeling the mushy spring of water.