tip- When playing as the class with the regular blaster rifle, make sure that you know that you have 2 different types of grenades. Don't be shy about using them. There are alot of ammo droids scattered through the levels as well. Also, make sure there are no green arrows infront of you, on your map, before you chuck 3 or 4 grenades.
Grenades keep other team from advancing on your position.