Being a fellow übermensch tanker, these are the pointers I can give you:
1) Always go for the gun with the highest penetration. This is often not the highest caliber
2) Against tanks of a higher tier than you or heavies, consider switching to HE ammo -- It'll do damage even if it doesn't penetrate
3) German tanks are excellent snipers. Learn where weak spots are and aim for them. Driver viewport, the lowest part of the tanks hull (if they're not in a hull down position), the back 3rd of the hull (engine area) and the drive wheels on the tracks are all good weak spots to go for. Ammo rack is also good, but the exact spot for that varies from tank to tank. Side/rear armor on turrets is typically lower than side/reat armor on hull while turret front armor is typically as strong as hull front armor or stronger.
4) Remember the angle you hit the enemy at will affect penetration, as will range
5) If you find something that you have no hope of damaging (especially as a light tank) remember that you get xp/credits for spotting a target while your artillery/heavies destroy it. Find a brush to hide in and profit
6) Tank destroyers typically have slightly better guns than regular tanks. The Marder II and Stug III in paticular are awesome. The Jagdpanther, Ferdinand and Jagdtiger are all p. decent. The hetzer is ok. The JagdIV is terribad.
QFT. Also:
7) Never park directly behind your mates - smart tankers reverse and hide behind cover for reloading (aka. peek-a-boo) and they'll rage hard if you block them.
8) Most American tanks have pretty good gun depression, so use that to get into hull down positions (here's an ilustration
http://upload.wikimedia.org/wikipedia/commons/c/cc/Hull_down_tank_diagram.png )
9) When you're facing other tanks try to angle your tank slightly (ca. 20-30 deg) - it will boost your front armor by few mm while shots to your exposed side will most likely bounce.
10) When you're playing a medium tank: flank often and flank hard. And if your attack is stuck in a chokepoint, don't be afraid to leave your heavier mates and go somewhere else in the map where you can tip the scales in your team's favor.
11) When you're playing a heavy tank: don't be a fucking pussy. Push when you outnumber and outgun the enemy, yeah, you'll take a hit or two but that's what you are for. Just don't suicide, check the minimap and count the enemies on each side of the battlefield before going in with guns blazing.
12) Best way to kill a turretless TD is to detrack it (shoot at either first or last wheel) and/or glue yourself to his side to prevent him from turning.
13) Choose your targets wisely. Some tanks have good armor but crappy guns (Churchill) and should be a low priority, while others have awesome guns but are made of paper-mache (Marder II, M18 Hellcat) and should be dealt with first.
14) You HE shots can penetrate some of the ligher armors (arties, low tier TDs) and will explode inside the enemy tank dealing more damage than standard AP rounds.
15) When playing peek-a-boo it's sometimes better to use R to creep forward slowly than go in full speed with W.
16) Save your free exp for shit tanks (eg. T1 Heavy). Basic rule is: if the tank you're driving doesn't make you want to commit suicide then it's not worth spending free exp on it.
Edit:
My Is-3 just got ammo racked by Su-5. Su-fucking-5. Fucking arty.