Back lighting really helps to show off clarity and colour of the beer. Focus is always important, sometimes those little point and shoot cameras get confused about what to focus on, so make sure that is right. An ample amount of light is always good for a picture, as I said back lighting is important but don't forget to light the front.
If you really want to get fancy you can make a light box, they are super easy to make a little cardboard box, a white sheet and some lights and you've got it made. There is a another thread floating around here with some very useful info on photographing beer. Hope that helps. I will try a track down that thread for you, interesting stuff!