In both cases, the trick is to use a lot of white and linseed oil. Glass is easy, because it doesn't require a lot of precision (if you're doing realism). Are you painting from "life"? The best thing to do is to look at glass, but stop seeing it as an object, just look at it's qualities. Often it's best to paint glass "last," on "top" of the background, using the background to incorporate into the glass object. Then distort and mute it using the white (with linseed oil) with long strokes (as transparent as possible) and add reflections. Be "light-handed," and even a little sloppy. Transparency is key, which is best obtained using linseed oil.
As for "candle light"--that is harder (at least for me). Again, use white, and yellow ocher, and again, use linseed oil. It might help to look at paintings that have candle light as a subject. The Baroque artists used a lot of candle light, to demonstrate a sharp contrast between light and shadow. A particular painting that comes to mind is Artemesia Gentileschi's "Judith and her Maidservant" (Sorry, it's not letting me copy it, but you'll find it if you goggle it.)
Good luck, and practice!
Oh, and in the case of glass, make sure you work while the paint is wet! Once dry, it's not going to give you the effect you want.