With the new map pack out and MW3 coming out in a couple of months I figured I give some tips on how to get good at new maps. For you class I would use something that you are comfortable and good with. Now you have to learn the maps, like where the best camping spots are, where the most popular areas are, and what kind of map it is. In order to do this I would recommend play the game mode Domination because it helps you to learn a lot of this very quickly. It also helps because it's harder to get lost while you are playing because there is always an arrow pointing to where you should go. Another thing I would recommend is finding an overview of the map on the internet so you can become more familiar with the map. It can also help you to find good hiding spots and quicker running routes. When you are playing be sure to take notice of how spaced out things are on the map. This will help you later if you decide that you want to try a different weapon. An example of spacing and how it relates to the weapons you might use is Array. Array is a very big map and it is also very spread out so it is good for sniper rifles as well as other long range weapons. Another example is Nuketown. Nuketown is a very small and cramped map which makes it good for shotguns and sub-machineguns. After you have learned this should be a lot more familiar with the maps and be able to know them like the back of your hand.