The nice thing is that you can apply this technique to all forms of carbonated liquid which gives you lots of opportunity for practice. Of course, sodas and other carbonated drinks wont get a head on them like a beer.
To really enjoy a beer, it must be the right temperature, have a good head (foam at the top of the glass) if appropriate, and still have proper carbonation as you begin to drink. It cannot be watered down from ice, or flavor tainted from a glass that smells of dish soap. Also, a clean glass is really the only way to fully enjoy a beer as it was intended, no plastic party cups!
Step 1: From Wikapedia about serving temperature
The temperature of a beer has an influence on a drinker's experience. Colder temperatures allow fully attenuated beers such as pale lagers to be enjoyed for their crispness; while warmer temperatures allow the more rounded flavours of an ale or a stout to be perceived. Beer writer Michael Jackson proposes a five-level scale for serving temperatures: well chilled (7C/45F) for "light" beers (pale lagers), chilled (8C/47F) for Berliner Weisse and other wheat beers, lightly chilled (9C/48F) for all dark lagers, altbier and German wheat beers, cellar temperature (13C/55F) for regular British ale, stout and most Belgian specialities and room temperature (15.5C/60F) for strong dark ales (especially trappist beer) and barley wine.
There is no way I could have said it better! : )
PS - the thermometer is just to emphasize this step is about temperature, dont use one like the one in the photo.