I'm as green as it gets when it comes to shooting clays, but this much I know. Anytime you shoot and you don't know where the shot went, it's a complete waste. (well I mean you know where it didn't go, i.e on the target, but was it ahead, behind, over, under??)
You need to practice, and start out with the easiest presentation where you will almost always get a hit. For me it was directly behind the clay thrower. When the first station is mastered, step away a few yards and try from there. Shoot as if you were still in the first position and if no hits, make little adjustments where logic suggests.
Keep the clay trajectory the same each time. Once you get one position mastered, move again 5 or 8 yards and start in again. Eventually you'll get a rough semi circle on each side of the clay path, all for a particular trajectory.
Then you repeat again, except change trajectory, faster, or a higher angle, lower angle, whatever, and get those leads mastered.
Also, as I just read on this thread (told you I was green), use a full choke to further emphasize where the center of your pattern is.