If you are using non-contrast paints, I find it easiest to not fully assemble the minis before painting. Paint the arms and shoulders separate so that it is easier to hit all that "chaos trim".
Make sure to leave your glue points unpainted. I use poster tac to cover those (and it makes a good handle when you stick in a toothpick).
If you're using plastic glue (which melts/welds plastic together), you need bare plastic for it to work right.
Cyanoacrylate glue (superglue) doesn't need bare plastic, but there's always the risk of the paint coming off at the connection, breaking the join.