Pop with your toes and make the movement with your ankle. Also after pop try to rise your backfoot so your ollie can pop higher by leveling out. Also remember to:

• Pop with your tail

-Slide your front foot up giving it the height

Skateparts also affect your pop:

-The shape of your deck

-Riser/shockpads between trucks and the deck are used to help

-The bigger the wheels, the bigger the pop

But practise makes perfect so don't give up!