Getting a consistent mount and smooth swing are keys to making hits on clay and feathered birds. Gil and Vicki Ash from OSP Shooting School have a drill you can do in your own living room to help you perfect your mount and develop a smooth swing simply using a flashlight as a muzzle indicator.
When my youngest son was 7 years old, he started showing an interest in wingshooting, so I started him off with a 28-gauge and the flashlight drill. Instead of a flashlight, however, we had to use a laser pointer as even the AAA-size Mini-Mag lights won't fit the 28-gauge bore.
We practiced his mount and swing for 10 to 15 minutes each day after school, and by the time shooting season came around, he was breaking birds from the start. I can't say it enough; this is probably the single best shotgunning drill I've ever experienced.