I work in a small shop, so I know the struggle. Modularity and mobility are key for my setup. Almost everything is on castors, and everything serves multiple purposes. For example; I've got saw horses that bolt onto my certiflat table for more flat fab space. I also have conveyor rollers that I can bolt onto them to use for outfeed rollers. I've also got a chopsaw stand that bolts onto it. I reconfigure them depending on the job and the phase of work I happen to be in.

I've also got a rolling scaffold set up as a material rack. I can store multiple tiers of materials on them, but they are still(somewhat) mobile if I need to rearrange. The weight limit is restrictive, they are only(safely) rated for 800lbs between the two. But they are still incredibly handy. If you're in the right place at the right time, you can find dented up shopping carts that stores are just throwing away. They are great for small drops and scraps.

Another thing is, go vertical. Don't waste precious floorspace on stuff that isn't being used regularly. Overhead storage is great. It works both ways too, got empty space under your table? I bolted toolboxes in under mine, along with a bar to hold all my clamps and grinders. I store sheets upright against the wall, and have a couple eyebolts with a chain and carabiner to secure them.

Annnd, another thing. Unistrut is great stuff. You can fabricate all sorts of attachments for it. Great for modularity. I use it in place of pegboard for some things. Good if you want to solidly attach a thing to a thing, but not necessarily permanently.