You should also get to know your default weapons before picking up the fancier ones on the battlefield. Being out in the open for too long only makes you a bullet magnet. The first Gears of War game popularized cover-based combat in shooters, and hiding behind a low wall is just as important today as it was in 2006. Use this time to get a feel for the cover system.
The beta has a training area where you can safely experiment with your weapons before going on to fight other players. Newbies should familiarize themselves with the basics. Image Credit: The Coalition What the heck is a Lancer?