painting dash trim pieces?

First off, it is a good idea to clean all surfaces before sanding.  If a surface is dirty you could be grinding dirt in with the roughed up material. 

I would use a plastic priming agent and then just lay down some high-build primer.  Get it nice and smooth and you are ready for your top coat.    The plastic primer that I have used before is called Adherto.  This is made by the House of Kolor, but there are others out there.

http://www.houseofkolor.com/hok/products/specialty.jsp

Good luck...

Allen

If you want to loose the texture. First clean. then sand with 120 grit paper. I use PPG products. So I use DPX 801 adhesion promoter (shake until pink) Then apply a high build 2K primer with flex agent. Sand with 400g or higher (if bc/cc) If there is any raw plastic after sanding re-apply adhesion promoter (prime if needed ( could use a aerosol flexible primer in a small touch up) Paint.

If keeping the texture I would just use a scotch pad with your plastic cleaner. If raw plastic or injected color use promoter.

thank you very much for your reply back... i wanna start a project on my freetime... ill keep ya posted.. thanks