Basically just do a diffuse as you normally would, then create a transparency map (grayscale). Reflections will depend on what engine you are using, but usually (unless you're using a real old or basic engine) you don't add any reflections to your diffuse.
One major part would be reflections, having something move across the surface. You can't fake this only with a diffuse texture as far as I know. You would also want a transparent material or at least an illusion of an inside painted in the diffuse texture. Maybe combine with having a transparent material for the glass,…