Some advice for randoms.
Know what your vehicles capabilities are. This helps you fighting with it, and against it if you come across it on the field of battle. Know your gun depression, so you can stay away from hills and rises. Know your armour's weak spots so you can keep them hidden. Know your armour's strong points so you can use them (e.g. strong turret = hull-down.) Know your rate of fire so you can decide if it's worth peeking to trade shots. Acknowledge your crew training weakness if it's less than 100% or if modules aren't unlocked and fitted.
Where are your team deployed, are they camping? Can you or your platoon shore up a weakly defended flank, or a flank just broken through? Watch the map during the game. An overextended light tank who thinks he's spotting for TDs that aren't supporting him will just get blown up pointlessly. An isolated heavy with no nearby support can be easily surrounded and destroyed.
Choose your fight with tanks you can penetrate. Relocate if your Tier V medium won't go through the Tier VII heavy armour on this side. Think about where are the enemy tanks likely to be and where you can contribute to spotting or damaging them.
So support your team in the way your tank allows you to and you can contribute to victory.
Perhaps the single most effective way to improve your win rate and contribution to a game is by teaming up with your clanmates to wreak coordinated havoc on the enemy.
(you can memorise exact numbers if you like!) but an understanding that you've a high or low penetration gun and the same sort of knowledge about enemy armour will be of trememdous use in battle.
if your crew isn't at 100% everything suffers, camo, mobility, gun handling, loading. Acknowledge this and reduce your aggression accordingly.
Aggression, particularly early aggression is the number 1 killer of players. Don't be aggressive too early, no matter what armour you have there's a gun out there to penetrate it. Often there are 4 of those guns pointed at exactly where you're going. Don't be aggressive.