You will need to sand the frame with a fine sanding block or 150 grit sandpaper. If you have really bad areas use 120 grit sandpaper or a courser sanding sponge.

Remove the dust with a vacuum and/or tack rag.

Now you can prime using a good universal quick drying oil based primer. Zinsser Cover Stain or Kilz will work well. After priming you can paint with your favorite brand and type of paint.