I just did mine. Not sure if it's the best, but here's what I did...
I cleaned the calipers w/ a wire brush wheel on my dremel. Then I sprayed them w/ some brake cleaner/degreaser. Let that dry. Then sprayed them w/ a rust preventer and let that dry. Then sprayed them w/ ~3-4 coats of VHT gloss black spray paint. They turned out pretty good.
On my last Supra I painted the calipers w/ the same paint I had my car painted and then brushed some clear over top. They turner out very nice.
I just did mine yesterday. I took pictures but hasn't had time to upload and save them on my computer.
Here's what I did.
1. Remove the caliper.
2. Plug the oil hole with a screw so water or paint doesn't get in it.
3. Spray caliper with brake cleaner.
4. Spray caliper with degreaser - use a steel brush to remove grease.
5. Water Rinse caliper.
6. Wet sand it with 600 grit wet sand paper.
7. Water Rinse caliper.
8. Let it dry.
9. Paint with black or gray paint primer.
10. Let it dry and wet sand it using 1500 grit wet sand paper.
11. Paint the caliper
12. Let it dry and wet sand it again.
13. Put another coat of paint.
14. Let it dry and wet sand again.
15. Paint the caliper again.
16. Let it dry and install the caliper after about a day.
1500 grit is to fine for a good mechanical bond. It's a good 1st grit if you are wet sanding a clear coat. 400 grit is more than enough, 320 will also work. VHT is probably the best engine paint (in a can) I've found. Duplicolor engine paint isn't very resistant to engine degreasers.