This post will contain some basics regarding the beer rating system, what to look for in a good beer, what makes up a beer, etc., and I will probably come back to it in the future to add things. If you have any questions about anything I write, please let me know and I'd be more than happy to clarify.
Beer ratings are based on Beer Advocate's beer rating system. This is a scale of 1 to 5 based on the five main components of tasting a beer, and the % of rating contributing to overall score:
To save myself from republishing everything Beer Advocate has already quite ably written, look here for descriptions of each category. There's a load of good information on this website, so we'll keep that website for basic reference and this one for my thoughts.
As you check out the ratings I give, keep in mind that these are relative to style. What this means is that if I give an Imperial IPA a 3.8 and a wheat beer a 4.4, it doesn't necessarily mean that I liked the wheat beer better than the IIPA, it just means that the wheat beer is great compared to other wheat beers, and the IIPA is not quite as great compared to other IIPAs. Cuz I like my IIPAs.
Head: The foam you see at the top of a beer is referred to as head. Contrary to popular belief, it's actually a good thing to have a lot of. Head can be fluffy, pillowy, foamy, sticky, non-existent, etc. Generally, I pour my beer right down the center of the glass and let the head do it's thing. If the head sticks to the side of the glass, that's a good thing; it's called lacing, and the more of it the better, in most cases. Great beers tend to form intricate patterns down the side of your glass. Sometimes you'll get a heavily carbonated beer that is 80% head when you pour it vigorously. Here you can cheat and start by pouring it down the side of the glass, straightening it up as you go. Whatever you do, don't pull the old frat party trick where you wipe your finger on the side of your nose, then stir the head with it (unless it's a Beast Light or likewise). That kills the head, which can hurt the aroma and mouthfeel of the beer.
Also, make sure you have a "beer clean" glass. This means wash your glass out using non-scented, powder detergent that doesn't leave any residue on the edges of the glass. Generally, this excludes all liquid detergents. Either clean your glass with a basic powdered dishwasher detergent, or just rinse it with water after you drink a beer. I don't know how sanitary the latter is, but I do it a lot and it treats a head well, and I'm not dead yet.
Glassware: There are all kinds of options for glasses you can pour your beer into. Certain beers require special glasses to be appreciated to their fullest. Most beers, you can get away with pouring into a typical pint glass, mug or stein. I prefer a snifter for beers with more intricate aromas, and generally those with higher ABVs. It's a good idea to get yourself a nice snifter if you like beer. You'll be glad you did. For more on glassware, check out: BA Glassware .