A starting kit for someone with no tools yet: safety gear first, then measuring and marking, one good saw, a drill/driver, clamps and sanding, with a power-tool path and a hand-tool path and a list of what can wait.
A drill, a saw you can guide straight, a level, a stud finder and a few clamps build most shelves. Here’s the short list by shelf type, and how to size shelves so they don’t sag.
A track saw breaks down plywood anywhere and stores in a box. A table saw rips narrow, repeatable parts all day but needs a 16-foot lane. Here’s how to choose for a small shop.
You already own the two tools that do most of the cutting and joining. The next purchases should make those two accurate, then fill the gaps your projects actually hit.