A beer tasting starts by first observing the beef. Take the time to notice the color of your drink: is it blonde, amber, red, red-brown, brown, orange-blonde...the color of the beer has a lot to do with the type of malt it is, and the ingredients and fruits that were used to produce it.
Also consider the foam: it should be firm, with thin bubbles and white in color. Remember that a beer that is slightly hazy and not transparent is a sign of bad quality - the exception of course being white beers, which are never transparent.