You could use Dexion strips (fix to wall) and hangers (Brackets). The strips allow you to put as many shelves at any height as you want. Hope that helps.
I wrote a post with a video on how to build a garage shelf. Maybe this will help you too - https://chascrazycreations.com/building-a-large-garage-shelf/
All types of ideas from other Hometalkers
The best garage storage shelves are the metal ones that hold any weight for the garage. They stand alone. Some people use wooden shelves that are old or abandoned book shelves, they also can hold a good amount of weight. If you need to install shelves attached to the wall you need to know the material of the walls, find the 2 x4 studs behind the walls and mark them (they make a tool that helps find the studs if you cannot do it on your own) and use L brackets to strengthen them. Hope this gives you some ideas to help you, Dana.
Here is a video with instructions: https://www.youtube.com/watch?v=cTxRBckenI4