We used the Proslat system in our new garage. Found it on Amazon. We are very happy with it. Super functional, lots of options and reasonably priced.

It depends on what you need to store in ours I built shelving which anchors on the wall and suspends from the ceiling to retain patio furniture while keeping power equipment accessible. Also use slatwall for vsrious tools

All depends on what you want and budget. My experience has been that ordinary standards/brackets and particle board shelving is the most cost effective option. Comes in heavy duty versions as well. Especially if you can buy full sheet of particle board and rip them down yourself.