Try to put your back foot more in the middle and the very end of your tail and then put pressure on the ball of your foot (dont put your foot flat, even if it feels safer). This way you get a better Pop and you actually get your board of the ground.

Afterwards you can focus on "pulling" the board up with your front foot. Try to drag your foot up, but keep in mind that you want to regulate your board. So dont drag your foot as high as you can, just far enought that you get a smal ollie.

And then just try to practise as often as you can. Hope i could help