You didn't say if your regular or goofy but doesn't make any difference, view the above clip, its more than than just doing push up's, adjust your hands for your height and lifting weight to your chest, position your hands to obtain the most/best lift, are your toes flat or toes pointed on the tail (?) are you using your toes to spring upward/forward ? Since your practicing on the ground or floor concentrate bringing your lead foot forward first to balance your weight on the board, forcing the board down the wave upon take off so not to fall off the tail, back leg will naturally follow your lead leg. You may also try poping up bringing your lead leg forward with back leg down on the board then using the down leg hand to push upward too until its all fluid motion. Standing up is more than just push ups add "core" exercises to your routine too. Since your on a 10 footer sounds like you're too far back on the board, find the sweet spot to glide the board over pushing the water under the nose.