The strategy that you employ will be based on your tank, equipment, map and match up so it will differ each game. For example, if you have a tank that is slow and lacks maneuverability, or your crew is poorly trained your best option to help your team is to take up the role of a sniper. Just remember that whatever you decide to do you will gain experience by moving and engaging in battle, capturing the base and most of all destroying enemy tanks. Other tactics are to play aggressively if your tank and crew are better than the competition or as a sniper if you are familiar with the map.