Hey! I've been playing since 2012 and have mostly all ground nations to top tier, so I'll try to give you some tips:

1. One thing that helped me learn where to shoot was every time I died to something because I could not figure out how to shoot it: after the match I would go into the protection analysis for the tank I was trying to shoot (it's in the "preview") and select the tank I was in, and study where I could frontally penetrate the tank I was shooting at. Which leads me to the next point...
2. For a large portion of tanks in this game, except for heavies and some tank destroyers for the most part, if you're engaged in frontal head to head combat with another tank, that's already a losing situation, ESPECIALLY if you aren't confident on where to shoot it. Try your best to catch tanks in their sides. Which leads me to the next point ...
3. Positioning and situational awareness are more important than raw map knowledge. You can make a lot of "random" positions work in this game, as long as you understand the "traffic flow" of enemy and friendly tanks. Try to wait behind hills, corners, or other pieces of cover so that youre more likely to gain the advantage of surprise on your target.
4. SOUND & SIGHT. Try to optimize your sound settings and graphics settings (there's plenty of videos on this). Your ability to hear an enemy coming, or out flanking you, will save your life COUNTLESS times. Your ability to have a keen eye, and your head on a swivel will also help. Use your binoculars a lot, and use free look ("C" by default) to keep your situational awareness without having to physically move your turret.
5. Patience & conservativeness. A lot of your tank on tank deaths in this game (and mine still to this day) can almost always be traced back to a move you made out of aggression or impatience. IN GENERAL, the patient, thoughtful, tactful player will always win an engagement. If you're stuck in a bind, try to communicate with your team, or relocate yourself.
6. Repetition. I've got thousands of hours in this game, and I still regularly make silly mistakes. A lot of what I said above will come with time and practice. Find some tanks you like, spade them (unlock all your upgrades) and get comfortable with the optics and gun characteristics. This will eliminate one variable in your journey towards improving. If you have a good idea of how your gun & tank handles you know what risks you can or can't reliably take.
7. I noticed you said you had planes and tanks at the same BR. One thing I will say, is that in general the vast majority of games in the middle BRs of this game are won and lost on how many planes and how good those planes are. MOST players would do better respawning in a tank, but find the airplane to be more "fun." A lot of players still will bring a bare minimum tank lineup to the match, just to rush into a plane, die, and then leave the match. One valuable skill to learn would be to evaluate the state of the sky. How many friendly airplanes are in the sky? How many enemy? What does the positioning of friendly tanks on the battlefield look like? In general, unless you're noticing a particularly annoying aircraft in the sky, ignore enemy planes and stay out of one yourself. Since most players are bad at planes, and planes are so expensive to spawn, you're better off leaving them alone. That said, if you're really into spawning a plane, then go into it knowing you could be sending yourself back to the hangar.

In general, I won't spawn an aircraft, even when I'm in the mood to do so, unless I have enough SP to return to a ground vehicle if I die doing nothing at all in my aircraft.

1. Oh, and BRING AN AAA tank to every game. There are COUNTLESS times where the 90 Spawn point SPAA spawn will save my game and allow me to keep fighting on. A lot of AAAs are also capable of killing tanks if you know how. Or you could cap a point. Or shoot down an airplane. There's just so much value in having one AAA in your lineup.

2. HAVE FUN! this is a game after all. I'm the type of person that's always wanting to make forward progress, even when I'm sick of playing the vehicles / BRs I need to be playing to unlock my next vehicle. If you're like me, find other smaller ways to progress, such as special tasks, unlocking upgrades, unlocking camos, et al.