I do it while on the ground, without making clicks

You must have your nollie shuvits unlocked, all you have to do is lean a bit back, throw it harder but not too hard, jump back and stay close to the board while you're in the air so that your board doesnt flip

Once you have nollie shuvits down. Throw it harder. For some reason, no one talks about the secret foot position. Angle the back foot at 45 degrees (like a kickflip) and have it just under your back bolts(closer to centre of board). My theory is that it helps keep the board level due to the pressure being applied. I worked this out years ago accidentally and have taught so many people