As everybody knows, before you start a battle you have 30 seconds to consider on your game plan which will make the difference between winning and losing. That being said I will enumerate various factors that need to be taken into consideration, some are very important some are less important.
In order to start a battle you have to have a good knowledge about your tank, what are its strength points and what are the weak points as these will help you create your game plan. you have to see on what category are you amongst your team's tanks as well, not only yours. Based on the map you are and on your tank's statistics you will know if its better for you to be in the middle of the battle or if to stay at a distance and attack from sides. If you have no armor for example, it is clear that you should stay at a safer distance and avoid to engage in close encounters with your enemies.
In order to start a battle you have to have a good knowledge about your tank, what are its strength points and what are the weak points as these will help you create your game plan. you have to see on what category are you amongst your team's tanks as well, not only yours. Based on the map you are and on your tank's statistics you will know if its better for you to be in the middle of the battle or if to stay at a distance and attack from sides. If you have no armor for example, it is clear that you should stay at a safer distance and avoid to engage in close encounters with your enemies.
After you made a clear view on this points try to predict what your team will do and other what other team will try to do. You have to make a plan and be ready to adapt to the changes that are taking place in your team's plans and the enemy's team. It is possible your team will go on a completely different plan and you will have to take new actions and make changes to your plan, don't let anything at God's will.