standing tall and good pop off the wake

[STALEFISH79]

ive been riding for a little while... i have all the basic grabs, 180s and a hs 3 down, im looking to start getting more out of my riding... actually paying more attention to the basics. i keep being told stand tall when getting into the curl and pop off the wake, im obviously not getting it right, i end up with a flat jump and no hang time.. ive also been working on keeping my hips up and back straight... is there some advice somone has that can possibly make me understand what im doing wrong or that im not doing at all? i want to max out my height and hang time. ideas?