HIDE THAT STUFF: Open shelves invite clutter. The horizontal surface is just too tempting to put something down for the moment and you'll get back to it in a few days, which turns into weeks and years. Shelving units are fine, but if you can put some simple doors on the front, you'll find yourself keeping things clean and out of sight. Framing with wood around the front of a metal shelf unit is not hard and lets you put on simple MDF doors. Get clever and space the doors out from the front of the shelves by 6" and you can mount shallow shelves on the back of those doors for paint cans or other similar clutter magnets.
I have kitchen cabinets in the back of my garage. It helps, but not as effective as I hoped. Drawer units are great for power tools and loose items. Open cabinet space do not work for cords, cables, or other loose stuff. That's where shelves with bins help.
BINS! Yes, I totally endorse a large quantity of identical sized bins. Cleans things up, makes it easier to organize all the loose stuff that falls over and spills over everything.
FLOORS: Before I moved into the house I purchased, I already spent time sweeping, cleaning, washing, and finally painting the floor with an epoxy coating (Rustoleum products). I had never done this before and I was amazed how much of a difference it has made. The floors stay cleaner. I can wipe up stains with a rag and cleaner. It does get chipped up and I will have to recoat it, but it's been over 6 years and looks good. I really does keep the dust down.
WHEELS. Pretty much everything in my garage is on casters unless it is a shelving unit or attached to the wall. A couple of times a year I would wheel out everything into the driveway to let me sweep and clean the floors and walls. It does attract people thinking there is a super awesome garage sale going on though.
LEAF BLOWER. No, seriously. I'm not kidding. An electric leaf blower works great to blow off the dust that accumulates on shelves, tool boxes, corners, between studs, on the vehicle lift, the floors, etc. I hate seeing all the cobwebs in the corners of the garage or the metal dust from grinding on the floor trapped next to the garage doors. Leaf blower is fantastic for clearing it out.
USE IT, STORE IT, SELL IT. I keep collecting tools at garage and estate sales. I slowly upgrade my tools with nicer stuff, vintage, or similar. I have a table saw in the garage that I have used all of about five times. It's taking up valuable floor space and I really need to just give up and move it to the shed out back. OR simply sell it at the yearly garage sale. How often do you use it? Can you use another tool to do the job? Do you REALLY need those specialty tools in your drawers, on the walls or shelves? While you want the tool, think over when you'll actually need it. I'm willing to let the tool store keep the tool I need on their shelves until when I need it, and then I will buy it as necessary. At least that's what I tell myself. It's hard to obey that guideline when so many nifty tools are on sale. Resist the urge! You can do - oooh, a cheap HVLP gun I could use just for primer? SOLD!
There's tons of organizing ideas here. Find a system you like and stick to it. I wish I had standardized storage options originally and now will have to redo it all to really be effective. That, and more storage sheds.