I’d love a sink but outside- save space and lets you be messier.
More lights. Basically work out the correct number of lights then add at least 25% more lights, it makes such a difference. And similarly, twice as much workbench as you think you need, so that you can start something, then do something else- I have enough workbench for any job I want to do but never enough free for the job I want to do right now. And of course lots of unassigned storage so that your needs can grow into the space that’s left.
I guess not everyone will agree but light coloured walls and floor really just make me feel generally nicer about being in the garage, wish I’d done it years ago. Everything’s brighter and easier to see, easier to keep clean too (which basically has made the difference between me actually keeping it clean, swept etc, and not bothering because it always looked like it needed done even straight after I did it)