As one can tell by my handle, that's what I do the most, shooting clays. First and foremost, the gun must be fitted to come up to your shoulder and cheek without looking to see if its right. Practice, practice, practice. If one is shooting skeet gun up (mounted before the call of the clay), then that part is not as important as you can settle in before the call. Face the furthermost house and twist partway back toward the the high house, station 2 for instance, about 1/2 way between the center stake and the house, cut your eyes about another 1/2 distance and say pull. As the clay (don't look at the opening) comes out keep your eyes on the clay and start swinging your gun, when you pull just ahead of it, fire, but keep swinging the gun (very important). That is called swing through. Don't stop the gun.
Sustained lead would be to.....again, face the furthermost skeet house, even on 4, I face the low house, and set up the same way. When the clay comes out get your gun in front of the clay establish the lead and and fire. Station 4 is around a 4 foot lead, 3 & 5 about 3. 2 and 6 are swing threws from the outgoing house and 2-3 foot leads from the incoming house. Station one high house line the gun with the stake, and when the clay just settles on top of the gun, fire. Station one incoming should be shot mid field with about a foot lead. On doubles maybe a little more depending where you catch it. Don't marry the lead. The goal should be to break most at mid-field. Different stations will require different leads, but after awhile the brain takes over and sees the proper lead. Did I say, don't stop the gun?
As one swings the gun a shot trail will result, somewhat like the water hose example above. Don't never ever aim a shotgun unless you're shooting a sitting duck. Point. Good shooters will select the point at which they wish to break the clay, and not really fully shoulder the gun until the moment of fire as they are swinging the gun and following the clay as they mount. Don't stop the gun.
Good luck. It will take about 1000 shells to get it down. The best I've ever done with a 12 was 135 straight. My favorite is the 28 as there is little kick and my scores are almost as good as my 12. The 410 is another story, lucky to get into the low 20's, but a lot of fun............and oh, don't stop the gun....................ck