I had a similar garage problem, just on a slightly larger scale! I had to make a list of rules for transforming my space to a workable and enjoyable workspace.
1. Use it or lose it!
I had to dispose of quite a few "passions" such as candlemaking supplies, pottery stuff, overflow from a beauty shop in addition to the detritus of life like old computers, magazines, furniture and such.
2. Do SOMETHING every day!
Some days were wire in the lift, burn the scrap pile, meet with 3 people answering the various ads to shed stuff and then lunch! Other days were throw out 2 cans of spray paint that were non sprayers.
3. If you pick it up, put it back where it belongs!
This one starts out hard but gets easier as you go along. As I waded in, I was proud of the new nice clean space but then used this space as I dealt with boxes of junk that needed processing. Might not have a spot set up for those trophy parts that only come out to build car club show stuff, but you might have them all in one tub.
4. Be ruthless!
Give ample warning to any other people with stuff in this space that since you are doing all the work, you make all the decisions. Yup, I sold your candlemaking supplies and used the money to buy a fire extinguisher and a paper towel holder...and a BBQ sandwich!
5. The floor is not a shelf!
This is a variant of rule 3 with a follow though of rule 1. And if something ends up on the floor, then the something you do today should be to make a proper spot to put these items at!
6. Your, mine, ours with a twist.
Sometimes you gotta kick stuff out and place it back on certain people that you have to live with. Please be careful with this one!! Kiddos have skateboards and paintball supplies in their space not this space. That bag of shoes that she is going to deal with "someday" might need an application of sternness...or not. Don't cut your own throat with this one.
7. Don't make it worse!
Spend the time enforcing your new garage rules by cleaning or organizing. Sure there will be time when you walk away from something with it scattered, these things happen. Get back to it soon though.
Like any habit, if you just keep doing it right you will discover that you just keep doing it right.
Bet you cannot even find the piano! I have no idea why I ended up with a piano!
Bruce