Initially, when this sport started, live pigeons were used. But then those species of pigeons came under the threat of extinction, which lead to the introduction of fake pigeons. Now, clay pigeons are used. There are several versions―Double Trap, Olympic Trap, Nordic Trap. In the USA, American trap shooting is the most popular form of this sport.
Don't be Trigger Happy!
This is a very fundamental and important thing. The trigger should not be handled or fidgeted with, till the gun is properly mounted, pointing in a safe direction, and is ready for shooting. So ideally, you should keep your finger out of the trigger guard and off the trigger.
'Choke' a Block
Practicing with an extra-full choke is ideal if you aren't doing so. The reason is, if you do that, you can learn precision shooting. The extra-full choke will throw a small tight pattern, and it will lead you to many missed targets. Using an extra-full choke will eliminate slop in your aim and shooting.