FRETS.COM
Shop Tip #367
© Frank Ford 2006; Photo by FF

Whatever you do, don't use metal shelf brackets for shop shelving.  Instead, make the shelving just exactly as you would a free-standing bookcase, back and all.  Then, hang the unit on the wall.  The difference in strength is really impressive, and because the shelves are nailed all along their backs, they will have far less tendency to sag.  And, you can vary the depth, length and width to suit the wall and the stuff you'll be storing.