How Do I Paint on Wine Glasses?

Be sure to paint only the outside, not the inside or the rim as most paints for glass are toxic. One brand is called Gallery Glass by Plaid. I agree with dedeswrkshop that an everyday design would probably get more use. You could always add a Xmas theme wine charm to each instead.

You will need the type of paint designed for glass. It is a special medium.
Most craft stores will have it.
Staying simple in your design will increase the charm of the picture.
If I were to receive a gift such as this, I would prefer to have an everyday design so I didn't have to put it away for the holidays. Something in grapes would be very easy to do. Or a tri-color pattern of some sort.