World of tanks, is a very complex game. Many of the tactics, works like a game of chess. When I get a kill, of a tank, on the enemy-team, but gets taken out, right afterwards, I get to think of the way pawns, bishops, castles and knights are set to work togther, in order to protect the king and queen in the game of chess. Each of those, have their way to move. Their own way to take out the chesmen of the other player. Those aspecs are similar to World of tanks. Each tank have it's own qualities and weaknesses, and along with the fact of whether you're buttom -or toptier, it determins, where on each map you should go with your tank.

Another thing worthy to compare the game with, is driving. As well as drivers are supposed to keep an eye in the mirrors, on the speed-counter behind the wheel, the tanker's supposed to keep an eye on the mini-map, in buttom right corner of the screen, as well as on the battlefield, to see where he is compare to his closest teammates, to make sure he doesn't take un-necessary shots from allies, by going straight in their line of fire. If you take damage from behind, and you know there's no enemy behind, that could have shot you, then it's most likely you went Into the line of fire of an ally, trying to fire a damaging shot on an enemy tank in front of you

Keep in mind, that which ever tank you choose to drive in, it takes time, to learn that tank properly. But once you know it down to the last bolt on each of the plates, that's when you're able to do increadible things in it. That is when you can do things in the tank, you see people do on videos.
Partly. Another thing, is to learn the mechanics.

If the opponent is angled or turned a bit sidewards, it's not much likely you will penetrate no matter the shell type. And better players most often just leaves the shell in the gunbarrel and never fire it, if it is such.

Snapping the shot can be good in some occations, but the likelyness that the shot will hit is bigger if you take your time to aim the shot first. If you snap it, it's more likely you're making holes in the ground in front of the tank, or shoot some small rocks loose. The shot should be hitting the tank, red/purple (in colorblind mode) 

Just because people are better than you, ok yes, it means they're more dangerous, because there are things they might know, but let me give you guys a challenge then. 
Turn off percentage-rated win chances, turn off your xvm scales at least in-game, and try to play for quite some time. See what could happen to your own performance, when you don't know such things.
Try to have only the tanks shown in the list as the next. Play as if it was only the tank you're meeting. And see what could come out of it.

Something, I have learned throughout my time of playing:
 

1. Open flanks, invites the enemy
If you see positions on the map, where hardly any of your teammates goes, you can be quite sure to meet some enemy tanks. It's rare, that lemmingtrain-technics have worked out for me. Not an idea to be in the front of it, because then everyone will shoot you, but neither to be behind, because then you should consider yourself lucky, to just get one shot of damage fired, if you go along. In the middle, well, just as you're ready to fire, allies will get in your way, or the oponents will either shoot you, or return to cover, because they have just fired at your allies. That, is why I think it matters more, and works better to make sure that all flanks are covered.

2. Teamwork beats selfish gameplay
When I have lost a game, most the time I have seen my enemy team, working much better together, than my own team have done. Though I have got advices on playing more for myself, I have seen that selfish gameplay, rarely worked. And that have been the reason why I haven't taken it in, if some better players should be wondering out there. There's more to the game, than statistics and medals. And my best games have been when I have seen the team, a random team working together, as the team they are. And no, I don't mean that I've been carried. Because of the critisism I have had, I have sort of learned to hate even victories, where I didn't get to deal a single point of damage.

3. Even premium-ammo can bounce
There is a lot of players, who don't get why I get so frustrated on the use, overly often use of premium ammunition shells. I won't say I can afford it. Money, shouldn't be owning us. We should be owning our money. This game, should be possible to play, even without the huge spent of money. Another thing behind, is that in the most situations, it's useless. If the target is two tiers below you, paper-thin armor and has low health. Waste of money. Snapped shots, misses with a bigger logically likelyness, or if the target is angled somehow, you can risk your shell to bounce. Again, waste of money.

4. Your placing on the teamlist, has nothing to say on the outcome
Top or buttom tier, is what doesn't make much of a difference to the outcome of the game. It's not like you win all the battles, in which you are toptier, or lose any battle in which you are buttomtier. But your gameplay, has to be effected down to some of those facts. Another thing, that tells if it's going to be a defeat or a victory, or maybe even a draw, is down to how well you and your team plays together, compare to how well the enemy team plays together. Teamwork, does have a bigger impact on the outcome of the game, than you would think

5. There is a reason why you are more tanks on the same team
If the idea really was that you should just play for yourself, maybe the game would have been constructed differently. If playing for yourself, then why on earth do you play a MULTIPLAYER-game? This is like chess, like I wrote up higer. But there are 13-15 minds, each with their ideas of how to win this game... -if it's even what want 

6. If the outcome doesn't matter, then why playing?
If you don't really care about if you win or lose, your gameplay will be effected. And a team can't win, if one doesn't have in mind to win. One, can make the difference.

7. You do have the mini-map. Use it
Some players seems to judged to their gameplay, that they don't use their minimap. If you don't react to what you see on the minimap, why do you have it? And you only piss teammates off, by ignoring your minimap. Would you have liked to die, doing nothing, because your teammates ignored the minimap, and stuck to their own plans? No. I wouldn't. So the solution is to pay attention to the minimap and not the least, to react to what you see on it.

8. Never judge the dog on its fur, the bog on it's cover...
...or a tanker by his stats. After all it's stats. Statistics. Average numbers. They can be changed. You only see that the stats are in a certain way, but not why they are that way. You can't by the stats alone tell if a player has low stats, alone that he is bad, or if he is relatively new. That, is shown other ways. Another thing, said very wisely, by a mod from one of the bigger streamers once; even a red player can pen your tank.

9. If you're afraid of your tank getting damaged, then why playing?
In world of tanks, heavies are meant to go to the fontlines, or the majority of them are. Some are meant as supporting, but still to shoot at targets. If you're afraid of your tank taking damage, then you play the wrong game. Also, there's not much to count on, once your teammates have fallen that you in particular, should be able to carry the team and save it all. Your team, needs your gun, your knowledge, and your firepower from the start. Not once they have fallen.Most tanks have a reload time. And if you're one against five, the likelyness, that you will survive, is very small. Not saying by this, that you should just brawl out headless to all the enemy tanks. But just that compare to what you might think, it would be an idea to get out there a bit sooner, than what is the current case of your gameplay. But notice how you do, and how your team does.

10. You need to be more *flexible*
Yup, it is a quote, sort of, from the Increadibles, but it is just as relevant in world of tanks. It's fine to have a plan. To make a plan while the timer counts down. But you have also to keep in mind, that you have 12-14 other tankers, with each their level of gameplay, skill and level of knowledge about the game mechanics. Each, their purposes and reasons to be here. And they might have other ideas. If you really want to be good, you take the challenge and fit your plan, to your team's gameplay. 

Good luck out there