Once you've decided on your glass colour, Brown or green etc (clear is nearly impossible on a 3D resin cast) paint the various tones of light and shade. Don't forget to 'capture' some colour from surrounding items.
If you look at some of the techniques used for painting metal using non metallic paint it should help.
Because it's glass then you want to get your final shine with varnish, not too much given the fact as you scale down the shine also dulls down. I'd try to avoid too much highlighting and go for a little catchlight on the rims.
Decide a fixed point for your light source and paint everything accordingly, jus as the flat figure painters do.
D.