A good way to get situated is Gun Game. It's pretty much … rush to kill to get through all the weapons. However, it teaches you to run, gun, and aim fast. After a few times getting kicked around, you start getting it.
I did this same thing with Counter Strike Global Offensive... they have a mode that's similar. This really helped to have a way that allows you to get used to a wide varieties of guns... and it really forces you to use and learn them quickly. It basically just gives you experience with the weapons... when you may not have used a lot of them overwise. It's helpful IMO.