Locate as many good reloadable hulls of a type that matches your shooting needs. Win AA, Remington RXP, etc. The shot, powder, wads, and primers will depend on what load your trying to make.
First step on most reloaders is the sizing and de-priming operation.
Next, the hull is primed.
Charge with powder from a powder measure or charge bar.
Seat the wad.
Charge with shot.
Start the the crimp.
Finish crimp and form the radius on the loaded round.
Various loaders will be slightly different on what is done in a stage, but all these operations get done in the end.
You may not save money in the long run, but you are very likely to shoot more, and get more out of your shotgun sports. Start with a single stage press like the MEC 600 Jr. It can make first rate loads if you pay attention to the loading manuals. Don't experiment or make substitutions of components not in the published data.
If you find you like shotshell reloading, you can move up to the progressive machines and really crank em out. I've been doing it since the late 1960s. There is alot of good used equipment on the market at ebay, and yard sales.
The photo shows 2 MEC 9000 progressive presses in 12 & 20 gauge and a MEC 600 Jr. tucked behind the left press. All the presses have Universal charge bars to keep tooling costs down.