Assuming you have a typical 20x20 garage with nothing on the back wall. The best storage solution is what came with my house when I bought it almost 40 years ago. A high, wide shelf/mini-mezzanine across the back.
First, the interior of my garage is unfinished and uninsulated. Like I said, it is more like a mini-mezzanine because it is plenty high enough
(about 60") to get the nose of a car underneath it or store other things under neat it
(bicycles, grill, etc).
Very heavy duty. The joist are 2x6 that run run across the width of the garage and are attached to the studs on the side (16" O.C.). The decking is actually 1x6 boards, but 3/4" plywood could be used. There is a center support that runs from the front joist down, at an angle, back to the bottom plate.
Because I am storing mostly heavy items on this, they are not very tall. I actually put another smaller shelf about 12-18" below the top plate that runs the width of the garage, I used HD metal shelf brackets with built in braces, the biggest ones I could find (16" ?) and then bolted on about a 20" piece of plywood.
(Picture below is from HD.) I used the lags into the studs.
This gave me a HUGE amount of storage, admittedly some of it is not easy to acess. The down side is, especially if you do the 2 tiers, you will be spending more than $150
You could always start with just the shelf about 18-24" below the top plate/ceiling. Depending on what you plan on storing, you probably could space the bracket (about $10 each) to every other joist.
If your budget is super tight, look for used/recycled kitchen cabinets. The fast and easy way to hang them is on a French cleat system.
