I have had numerous occasions to use small amounts of spray paint in my never-ending cabin building endeavor. I hate to spray a little and then have the can go bad from having the nozzle plugged. First I pulled the nozzles off and dropped them into a tub of paint thinner (the plastic tubs chicken livers come in). This worked well when I was only using Rust-Oleum paint. Now I have added the new Krylon "Special Purpose Camouflage" paints in various colors. It turns out the nozzles are not interchangeable. I learned this the hard way--paint all over. I needed a way to clean the nozzle and immediately put it back on the can. Here's what I do now--
When finished, hold the can inverted and spray to clear the pickup tube of paint. This only takes a few seconds. Next remove the nozzle and use brake cleaner (I starting using it for gun cleaning in place of Gun Scrubber years ago due to price) to clean the nozzle. The red spray tube will just fit in the bottom of the nozzle (be careful not to let it backspray into your eyes though!) and the brake cleaner acts the same as paint thinner. I then clean the last bit of residual paint from the spray hole by daubing it with a McDonald's/Arby's/Hardee's napkin.
If you do this you can use a small amount of paint and have the can act like new weeks or months later. Oh, I do invert the cans every couple of weeks or so in order to cut down on shaking time.
Hopefully, if you occasionally use spray paint this tip will make your time here today pay for itself.