My first suggestion is to practice shooting stationary targets (building column, tree). Do this while jetting up, down, side to side, back to foward. Keep doing this till you hit your targets often back to back. Pay attention to where you need to place your reticle in reference to the target based on your speed and direction.
Then start playing LakRabbit and Deathmatch using spinfusor only. No other game type allows for as many MA tries per minute. No chain, no GL. Disc only. Yeah, your gonna get your butt kicked in Disc only DM. But your learning. I ususally do this for 30 mintues to an hour before I play CTF. Do this everyday and there will be improvment.
Some basic rules: One of the most common defensive movements is for a target to stop jetting and start dropping for faster movement. So many of your MA's will involve shooting a dropping target. Learn to shoot below dropping targets. By the time the disc gets there, they will be dropping into it.
When dueling 1 vs 1 in the air, most MA's dont' require that much lead. About 1/2 a reticle width at the most. Also pay attention to the target and it's movement. This isn't a twitch reflex FPS as much as other games. The targets are usually slower moving to be patient, line up your shot, take it.