Keep a variety of ammunition available. You will need armor piercing rounds against some targets, while others just need high damage ordinance.
The type of map a battle takes place in will determine your overall strategy. Smaller and more cluttered maps require a slow approach while avoiding enemy fire and finding a location that offers a good vantage point. Larger and open maps allow you to attack enemies at a distance and has a better chance of completing a "capture the base" win.
When possible, get a second tank so you can continue playing as soon as your first tank is taken out.