BladeTech holster is the best you can buy for sensible money if not the best for Prod. out of all choices. It can be used in IDPA as well. Get DOH one.
Belt - get CR Speed or Double Alpha or something of two-belts design, inner that goes thru pants' loops and outer that attaches to inner belt with Welcro. Get one size larger than you normally wear.
5 mag pouches is ideal, 4 will do.
I'd go as far as to say that 5 mags is minimum, more is better but you normally won't need more than 6 per stage, unless you shoot USPSA where some stages are minimum of 60 rounds

Pouches - CR Speed or Double Alpha are good.
Get good shooting glasses, try them on, move eyes side to side and see if there is any distortion and/or it gets fuzzy. Yellow is good for dim lighting, red or copper is good for summer days outside.
Get good headset, try them on. It should sit around your ears, not ontop and pushing on them, or you'll get tired fast. Peltor Ultimate 10 is excellent and cheaper, I got one as backup and for visitors.
UpLULA is a great mag loading helper.
Mag brush like Arredondo is great for outdoors when your mags get dirty been dropped on the ground.