The trick is to get the crew training points up, you can increase the view range. If the enemy tank has a longer view, and better rangefinding they will see you and hit you more accurately. Having a lower tier tank with a fully trained crew is often more effective than having a higher tier tank with a crew that has little experience.
It pays to figure out the weak points on tanks. The Tiger is almost a one shot kill through the drivers slit, and the Russian stuff is vulnerable in the lower hull behind the turret. Catching a tank on fire is a great way to render it defenceless while you hit it again, and if they run out of fire extinguishers, or don't have any, they will die pretty quickly. Shermans are quick kills if you can hit them in the sides. You can hit almost any tank smack down the barrel and wreck their gun.
It's a toss up between keeping on the move, or finding a good place to set up camp so that the terrain is protecting the hull. There are some hard to find spots on most maps that give you a huge advantage.