Take your time, light even coats and a lot of them.
Some things that I found out.
1. Get a spray gun handle if you take the spray paint route. Did 2x 10 gal
tanks 4 sides, and my fingers where useless for 2 days, and couldn't feel them for 1 day. Spray gun handle saves this problem.
2. Don't buy cheep paint! Can not stress this enough. Bought 3$ cans at Home Depot and then 99˘ cans from Lowes. Went through 2x the cans from Lowes and they still didn't look good when finished.
3. Use cardboard to mask off the top of the tank. Used paper on a couple of them and it would suck up the paint and sag/fall apart. Cardboard worked for me better.
4. Get the REGULAR painters tape NOT the delicate surfaces one.
5. Get more then what you think you'll need. Saves a trip in the middle of the day half way done. You can always return the extra when ever your free.