Heavy Tanks
Heavy Tanks... the bruisers of the battlefield.
With armor enough to withstand great amounts of punishment and guns with enough power to penetrate almost any other tanks on the battlefield. What they lack is speed. They tend to be slow and rather un-wieldy.
Low Tier Heavy Tanks tend to be rather weak but like all new tanks, they get better with progression.
The Tactics for Heavy Tanks tend toward using angles to improve armor thickness and pinpoint shots to weak areas in your ooponents armor. This is a knowing aspect of tanking in World of Tanks. This is not a "could" know situation... it is an absolute "need" to know situation.
Keep repair kits and first aid kits handy under your consumables. Even better would be a tool kit to decrease your repair time. Ventilation, advanced gun laying drives, and shell rammers are also very important pieces of potential equipment.