To paint your tow mirrors here is what to do:
1. Wipe plastic with good prep degreaser (very important).
2. Rough sand with a DA and 180 grit.
3. Hand sand with a soft block with progressivly finer paper down to 600
4. Wipe plastic down with rubbing alcohol to destatic them.
5. Prime with etching primer (I recommend Dupont aerosol). I know etching primer is for metal but it will bite into plastic also.
6. Spray basecoat. Sand with 800 if any imperfections
7. Spray clear. If your gonna wet sand and polish, sand clear with 2000 down to 2500 and polish.
Do all painting in 1 day so you will not have to scuff them for the next application.
I painted my TTT mirrors and fender flares and turned out great.
Good luck, hope this helped. Let me know if this was not clear enough for ya