Best place to start is finding out what kind of matches are being run at the clubs and ranges nearby.
Then go to the sanctioning organization web sites and download the rule book.
The more popular matches are usually idpa.com, uspsa.org, also the home of the Steel Challenge matches, ICORE revolver matches, NRA Action Pistol.
Walt Kelly, alias Pogo, sez:
“Don't take life so serious, son, it ain't nohow permanent.”