Your shop looks pretty decent. Here are a couple things I would do:
Dedicate one wall, or as big of an area as possible, to a shelving unit. Store-bought, or self-built. Now the big key here is to absolutely maximize your shelves: don't have any dead space. For instance, if you've got a bunch of valve covers, intake manifolds, water pumps, or cylinder heads, those items don't stack well; you only need about 9-12 inches of height to store them. If you put them on a shelf that is 18-24 inches tall, you've wasted space on your shelf. I store things in blue plastic clam-shell lid tote boxes. They're 16 inches tall. If you have your shelves spaced 20-24 inches heigh, you've wasted 2-6 inches. If you have 8 shelves, at an average of 4-inches of height per shelf wasted, that's easily enough to add an extra shelf to your unit. Now, if your shelves are 6 feet or 8 feet long, you've just gained 6-8 feet of free storage.
I've got my big shelving unit maximized to the accomodate the blue boxes, and then a short shelf for heads, intakes, valve covers, etc.
Looks like you've already got some closet shelves (wire shelf) along the top of the wall. That's a good deal. I like that, too.
How tall is your ceiling? If it's 12 feet, you can build a storage closet in one corner and put all your cleaning supplies, air compressor, shop vacuum, brooms, etc. inside it, and make it have a 6.5-inch ceiling. Then the top can be used as a storage loft. I've got one in my 32x40 shop, and it gets A TON of junk off the floor...big, awkward junk.
How about shelves or a storage cabinet about the garage door. Usually wasted space there.
I noticed you have a shelf with a ton of aerosol cans on it--if you have a lot of spray cans, buy a plastic milk crate (or two), tip it on its side, and lay your paint cans on their sides, stacked in the crate. That has several benefits: you always see the lid of the can you're looking for, you never have to search for the can you're looking for, you never tip over the cans in front of the shelf as you reach for the cans in the back, and the paint mixes quicker because the solids are spread along the whole height of the can rather than all settled down at the bottom. It also saves a lot of room storing them.
If you have anything that's too good to throw away but not good enough to keep...throw it away. You won't miss it, even though it feels like you will.
I have a problem with clutter in my shop, and garbage. Clutter accumulates on any horizontal surface within 3 feet of a door. If I have something that needs to go in the shop, I step in the door and set it on the bench/shelf/parts washer/cart, thinking I'll put it away the next time I'm in the shop. VERY bad habbit.
I also used to have a problem with garbage in my shop--tags, wrappers, plastic bags, empty soda cans, etc. Anything that should hit the garbage can. Problem was, I only had one garbage can in the shop (32x40), and it was always on the other side of the shop, so again, I'd set it on the bench and figure I'd throw it away at the end of the day. Never happens. Now I have a garbage can in the front and back of the shop. At least I've solved that problem.
White pegboard and white painted shelves also give the appearance of a bigger, cleaner and more open shop, because there are much fewer shadows, due to the light reflecting rather than being absorbed. It makes the shop not only feel bigger, but it appears bigger, and more open.
Brad