Joints how to paint em

How do you guys handle painting joints? I have heard of sanding the joint but how do you do it? Any other tips?

Yes, this is a problem for me, too. Can any of the more seasoned customizers out there lend their skills to us?

I try to avoid painting joints and just use rit dye. Saves the worry of paint chips. Aside from that I got no advise myself.

I try my best to avoid painting arms by choosing a good pair with the base color I'm looking for, if at all possible. Depends on the figure and how much I plan to use it (pose, play, whatever). A couple of tips:

• Sand the inside of the shoulder joints on the torso (the friction of the shoulder peg should be enough to keep the arm posed, unless it's a worn-out arm)
  
• Sand the elbows (I haven't quite figured this out, myself, but I've trimmed around the joint in hopes the paint won't peel).
  
• Use a sealer (clear coat or top coat. I use Testor's semi-gloss, and it really gives stuff a Hasbro look. Not guaranteed to prevent chips, though)
  
• Use a primer (a basecoat will sometimes help prevent chipping, but not necessarily. I've used real primer on missiles yet still had the paint flake right off)
  
• Experiment with a pre-paint acetone wash (SlayerDave mentioned using acetone to prep Project-ARAH parts for paint because it "opens the pores of the plastic". It can also EAT plastic, but I think there's a balance to be found there. By "roughing up" the slick surface, the paint should stick better and chip less)

I'll pop the elbows off the rivets and sand down the elbow curves A LOT. Also sanding the circular part of the arm peg(the up/down point of the shoulder) will cut down on that chipping. Requires a demel dental bur tip though.
I'm interested in this acetone method.