Please research your guns, clothes etc. (see links), ask lots of questions.  There are guns for the very competitive, and those for enjoyment.  This is only my view point on a great sport.
Shotguns limited to models manufactured before 1899, external hammer side-x-side, Internal hammer side-x-side, external hammer pump (Winchester 1897 only) or external hammer lever. (or replica of)

Side By Side (External Hammer)

Side by Side (Internal Hammer)

Coach Gun

Winchester 1887

Winchester Model 1897