Assuming your draw length is correct and you're not over-bowed, the draw arm shoulder is most often the culprit of a pin that floats excessively. Whether its up and down float or left and right float is a result of how one grips the bow, when the culprit is the shoulder.
We're all a little different in how we do things, but here the routine I use that helps reduce pin float from a high shoulder:
After placing my bow hand on the grip where it needs to be, I ensure my release is placed correctly in my hand. I raise my bow arm and draw arm and expand from the chest while straightening my arms, and come to full draw. Before anchoring and looking through my peep, I tell myself to "settle my shoulders". That's when I let my shoulders relax and allow the head of the humerus to settle in to shoulder socket, and then I relax in that position. I then anchor my draw hand, nose on the string ever so lightly, and finally anchor through the peep. My draw hand is positioned and ready to execute my shot. My pin is on the target. I apply the slightest of forward pressure with my bow hand. Just enough that the pin settles as much as it will. I then begin to pull through my shot. There are several ways of thinking about how to pull through a shot. It all depends on what the steps mean to you in your mind. But it's all accomplished the same way. Some people think about pulling their elbow straight back. Some people think about pulling the clavicle in towards the spine. Some people think about expanding from the chest. Or maybe you're a command shooter, which is perfectly fine so long as you consistently stay fully against the wall of valley. If you're a command shooter, slowly squeeze the trigger while you're focused on the pin over dot. But focus on aiming more than focusing on squeezing the trigger.
There's some argument over weather focusing on the pin or focusing on the target is correct. The Marine Corps taught me to focus on the clear tip of the front sight post, so because of that I focus on the pin with a slightly blurry target - you do what works for you. For me, with focusing on the pin and having a blurry target, I perceive less movement of the pin, which helps relieve any anxiety over executing the shot when the pin is just over the dot on the target. But you'll need to experiment and find what works for you.