If you really want to find out if you suck or not, you need to stick at it for a few more hours or days. You also need to learn the map you are playing inside and out, otherwise you'll be getting p0wned by campers/those who know the map thoroughly.
I suggest picking one map and playing it over and over for a while. Another suggestion is to find a server with some good people on it (age above 14 or so and non-clannish) or you are going to get insults thrown at you. A good hint to change servers is when the whole clan is playing on their own server and you are just fresh meat and keep getting blown away. Find another server with some debutants on it.
I noticed a remarkable improvement in my aim after a week or so, plus I kept upping the response settings on my mouse every other day or so.You really get some twitch reflexes after a while
Of course, being almost 39 my reflexes aren't exactly the best anymore...