Pick a gun game, poll the field of competitors performing well, then test drive the gear if possible. Doing this will get your gun and gear selection narrowed down to the most viable options.

After that its all about honing your skills so you can make the most of what you have chosen to use. In the practical pistol shooting sports like USPSA, IDPA, or Steel Challenge it's usually the Indian not the Arrow getting the job done. You also don't want to hobble yourself by choosing a gun or gear that goes against the grain of what is needed. It also has to function reliably 100% of the time. I have seen more match performances trashed because of unreliable equipment than using less than optimal gear.