Keep at least 1000 rounds of ammo for each of your weapons on hand and ready for transport or use. Fire your weapon often enough to maintain a high level of proficiency. Rotate your inventory of ammo - if you fire 50 rounds in practice, use the oldest ammo in your stock and promptly replace it with new. The latter two are preferred as they are somewhat more effective. No handgun, not even a magnum revolver, is effective at more than very close range on soft targets.
Body armor is effective against all common handgun calibers.
Controlled expansion hangun bullets have high shock capability while retaining weight for penetration. Ammunition reloading is the practice of recovering expended cartridge cases, sizing the brass, and recharging with primer, powder, and bullet. Only Boxer primed brass cartridge cases are suitable for this purpose. A modest investment in reloading equipment can result in a considerable reduction in ammunition cost if fairly high volumes are involved. This is especially true if a group of shooters who regularly use the same ammunition type combine time and resources to produce their own ammo in quantity.