I shoot TONS of clays.
Sporting can be shot with any shotgun that can hold 2 shells. No single shots, since they do throw true pairs at some stations.
Most people do not shoot a pump. O/U's, and Semi Autos are mostly used. Some use SxS's and a few use pumps. I own all kinds of styles and makes of shotguns but I usually use one of my 500's.
I love a pump gun and since I hunt with them it makes sense to shoot Clays and Skeet with them.
A shell belt really helps. If you are shooting a 50 target course then it helps if it can hold 2 boxes. If you have one that only holds one box then you will need a bag to carry the rest of your shells. On a 100 target course a bag is absolutely needed.
If you are planning on changing chokes at each station then do that BEFORE you step up to shoot.
When your squad gets to each station ask to see the birds. Then decide on what choke you will use for the presentation. Once you get up to the line there is no changing chokes. All this only matters if you plan on, or can change your chokes. A lot of folks just shoot a Mod or IC for the whole course. That is up to you.
On some of the bigger courses a motorized cart is a good choice. Most of the real good courses offer rentals of carts. There are even courses that do not allow motorized carts at all. These are usually smaller courses and the walk is not that bad.
Other than that it is fairly simple. Pay your money. Shoot the course and HAVE FUN!