Now lets get one thing straight if it's not apparent already: when it comes to painting I AM AN AMATEUR . I have painted several cars and 2 trucks [the neighbor behind me hated me for it, but that's another story] and lots of bikes but no shop ; spray booth[that would be soooo nice to have] and add a sand blast cabinet to list that also.
I have hung rims to spray using the "spoke " method and it works nice for spraying.
But ......Sometimes I wish to paint a wheel without removing the spokes.
I have had excellent results with a small, fine,[not a cheap one] artist brush and a 1 inch foam brush....... One Shot brand paint.
A word about One Shot. It is expensive,but if you ever use it you will be amazed and it will become the only enamel that is brushed on you will ever use again.
Don't attempt to hand paint a rim with anything else. you will get nothing but runs and "thin spots"
I clean the wheel and sand out any pits.
Place an old fork in a bench vice and mount the wheel.
very steadily, using the artist brush paint between the spokes as I rotate the wheel.
Then with the flat 1 inch foam brush I apply paint to the sides while rotating the rim.
The next step is selecting a color of paint for the accent stripe or stripes. Any brand of paint can be used for this.
After the freshly painted rim has set up at least a week I once again mount the wheel in a fork : fill up the old bugler pin stripe tool [worth it's weight in gold] and hold firmly it against the fork with its small striping wheel against the rim.
With the bugler tool steadily against the rim with my left hand, I rotate the wheel 180 degrees with my right hand and Bingo! A perfect stripe. Then just repeat.
I keep a can of solvent with a rag handy if I mess up. simply wipe off and try again.
Small cotton swabs are essential . If dipped into solvent you can smooth out any uneven spots.