Painting Glass

I apologize for this inferior photo.....photography is not one of my better skills.  But, working with this photo, you can see a glass object with some pattern to it.  My best description of painting glass objects is......Don't paint the glass, paint the air inside and around the glass.  In other words, the background is green so paint the glass green with white to increase its opacity and darker shades of the green to show its form and shadow.  Avoid pure white highlights.  Tint your whites a bit.