Okay, first off, if you're using a hand thrower or a Wal Mart spring thrower, use a Skeet choke. As someone else said, success breeds confidence, and anything tighter than a skeet choke with a hand thrower is ridiculous.
Secondly, point the gun, don't aim it. It's not a rifle, it's a shotgun. If you're shooting with 1 eye closed, you're doing it wrong. You need to learn to shoot instictively, and thinking about leads and anything else is going to cause you to miss targets/birds. When I stopped shooting sporting clays for a couple of years, I went back and found myself hitting 20 less targets (out of 100) than I used to average, and it was all because I was overthinking. A few times rabbit hunting fixed it because I didn't have time to think: it was just point and shoot.
Lastly, and most importantly, make yourself keep swinging the gun after the shot. Focus on it. Exagerate it. Do it to the point that everyone around you is laughing at you. If you're stopping the gun when you pull the trigger, then you're actually stopping the gun BEFORE you pull the trigger. You need to train yourself to follow through on your shots, if you don't then you're going to be behind the bird every single time.
I've shot skeet since I was 7, and sporting clays since I was 12. I'm 25 now, and what I've learned in that time is that I miss birds because I'm overthinking or because I'm not following through on my shots. I used to be able to run a 25 straight every day I shot skeet, because I was just shooting. After getting away from shooting sports for a while, I found myself trying to remember leads and then trying to get my gun the correct distance in front of the target and pulling the trigger and stopping the gun.
Shoulder the gun, swing it left and right, get a good feel and make sure to shut off your brain. Just point and shoot, and you'll start hitting more birds.