I have been getting mixed info on how to hit a jump. Some of my friends say they jump evenly off both feet, but other friends say that they ollie by doing basically a tail press mid way up the jump then popping off the tail as the nose leaves the jump. Which is right? when i hit just i try to pop off evenly, but my board always slips out to behind me and i either land on my stomach or barely on my toe edge. Could someone give me the proper way to hit a jump, get air, and stay balanced?
With jumps you want to be evenly jumping off both feet. That's called a pop, which is always done evenly off both feet, kind of like doing a hop off both feet.
Ollies are typically used for flatground tricks or some rail/box tricks, whereas you use pop for jumps because it's a heck of a lot more stable (and stability is the key to hitting jumps - not height).
You want to pop instead of using ollies off jumps because pop sets you up for a more stable air and ollies off jumps can be unstable, especially as you start doing bigger jumps.
As far as where you're going wrong, I'd wager you're leaning too much in one direction/bent upper body and not popping evenly and balanced. Either that or you're focusing on popping too hard and making yourself unbalanced by trying for power instead of stability. Pop is all about stability, not about how hard you can pop.
Make sure you're timing your pop correctly too, you should be popping as you ride up the ramp, not just at the last second (see attached photo below for timing of pop).
Ideally, for a straight air pop, you also want to be on a tiny bit of toe edge. Not enough that you're turning, but rather you're riding in a straight line with a tiny bit of toe edge pressure as you pop. This helps you stay stable as you pop.