There are machine guns on some tanks. those are mainly for fighting tanks that dont have armor everywhere, so you dont need to waste grenades on those so called tanks. also, there is an indicator in form of a cross that shows you your chances on penetration. green means easy to crack. yellow means less then 50% chance to penetrate. red means dont even try. also, standing still while firing gives you more precision. finally, having different types of ammo can be useful in different situations and gameplay styles. Last but not at least, dont use mobile anti-aircraft guns against tanks, but against aircrafts as you are supposed to do.

Capture points are there for a reason. capturing them that is. that btw gives a lot of points too. standing on hills will allow you to see and shoot further, but makes you an easy target while standing lower makes it hard to hit others but also makes you hard to hit. keep your front armor from being pointed directly towars your enemy, rather use a 45 degree angle, making both your front and side armor harder to penetrate.

If i forgot something, please tell me in the comments.