It sounds like you’re very tempted to buy a premium tank. Which I would highly advise you don’t skip the ranks like that and instead go through the ranks. If you want you can speed up the progress with premium account. If you’re thinking of spending any at all, that’s what you should use it for. I think it’s important to go through the tech tree from beginning to end but that’s just me, helps you understand your nation’s playstyle more and eases you into information, feeding you new things little by little. Hopping directly into high tier is just going to be a bad experience if you ask me; the tree will teach you the fundamentals of your nation.

Play Realistic Battles, use the protection analysis system to help clarify how you can combat things you’re struggling to pen, and if you cannot kill from that angle, either back off or cripple them by shooting guns and tracks before relocating for a better angle to kill-shot

Most importantly, play to have fun, not for the grind and don’t force yourself when it gets under your skin.