Before you go out ill try to give you some tips of things I have to work on to fix my 3s because they are kicking my fucking ass. First off, I learned 180s wrong, i would whip my board around under me instead of rotate my head and upper body...this causes a lot of problems jumping onto rails and boxes and can throw off my commitment on jumps. So first and foremost (if FS is easier like it was for me start working on that) practice good 180s where you pop, bring your board up to you with your knees bent and rotate your head. Un learning the wrong way to spin is being a bitch for me. At home not strapped in or anything practice jumping up and spinning the 3 while keeping your knees bent up to you (so you aren't straight legged). Then when you take these to the jump that will hopefully get you comfortable with a good pop and a clean rotation. Speaking of pop it will be very important, you dont need a ton, but to do tricks off jumps and get good air you need to pop, so really get comfy with a good control pop off the jumps before you start spinning. Through trying 3s the last week I have really figured out what im doing wrong but just cant dial them in and clean them up to the level I want, and im going to attribute some of my problem to not learning the basics correctly, so while you might want to jump head first into spins dial that shit back and work on good pops with good straight airs and grabs to control your self in the air. It would probably do good to spend a day just working on good air control, learning grabs, and doing 1s