Snowboarding question...?

Ok so I am 16 and am now an intermediate snowboarder I guess... I shred down the hill, do jumps and flatland freestyle tricks and stuff like that, but I am having a little trouble. I am confused on how to jump, ollie, bunny hop, whatever you want to call it. I was just wondering if to do it, do you jump up with both feet at once? Or do you lift your front foot up and then your back? I think I am doing it wrong because every time I go off a jump, either my front goes too far up, or I land sideways. Please help me out. All help is greatly appreciated. Thank you.