I remember the feeling you had. “How good am I?”, you ask, you want to know your rank. I’ve been there and I’ve gone in too early. I got placed in low gold, then I dropped to low silver because I wasn’t ready for gold. Now I’m solidly at high gold to low plat whenever I play comp, but it was an annoying climb, because I was doing it before I was ready.
The current season will last for 40 more days, so you’re in no rush in that regard - try to be ready.
Being ready means:
a) knowing your heroes
b) knowing the other heroes
c) knowing the maps
(d) knowing compositions, counters, strategies,…)
a) Shouldn’t be a big problem. As a tank, you’re in a minority, which means that in most games, you will be “allowed” to pick a hero you’re comfortable with. As long as you’re capable as a main tank (Rein, Winston, Orisa) as well as an off tank (Zarya, D.Va, Hog), you should be fine in most cases. Nothing worse than switching to something you can’t play in comp, because there are no other tanks/supports.
b) You should be able to identify every hero through their portrait as well as their sillhouette (maybe even the sound of their steps) and without long thinking be able to recite their abilities (not the names, but what they do with it), including ultimates. Test yourself a bit whether it works. This goes for opponents as well as team mates. You should know how your healers operate, so you can actually get healed when you want to. There’s also voice lines - think of a hero, try to remember what they say when they use their ult (for most heroes, the voice line is different whether it’s on your team or the opponents’). Also: know the ult, know how you should react.
Second part of this is counters. Knowing abilities is one thing, but you should be able to immediately realize whether a certain hero is good against you or not. Oftentimes that’s just a memory of them being annoying to you, nothing well-thought out. It’s important though, because it encourages you to play around them.
c) When the screen says “Anubis: Attack” - do you know, what the spawn room will look like? Do you know, which map type it’s going to be? Do you know where the first route to go leads and what to watch out for? There are 20 maps right now. 15 of them have an attack and a defense side, the other 5 have 3 sub-maps each. You should be able to know what will come before you actually see it, while seeing it will hopefully give you an even more detailled information about the map.
Every know and then, while you’re not fighting, ask yourself: where is the next mega healthpack? Where is the next small one? Is there a way for opponents to get behind you in the current position? Is there a way for those that can climb walls or have other vertical movement? One of my earliest comp games, I didn’t find the stairs for the high ground where the rest of my team set up defenses. Felt really bad. As a tank, you won’t often go for health packs, so this is no conditio sine qua non as they say, but if you find that you have no clue about health packs, go look around a bit.
Ultimately, you will keep on learning the game, and the stuff I mentioned for point d) is pretty much endless, but for the most part it will come bit by bit. For now, you want to know the maps and the heroes at least enough to feel at home. It’s a game, it’s about fun. Feeling out of place, not knowing where to go, making a stupid mistake because you didn’t know what D.Va’s ultimate is - that’s no fun.
Mystery heroes is a game mode that might help you to learn more about the game - you will see a larger variety of heroes, both as allies, enemies and for yourself, and you will experience all the possible matchups. You might be a Roadhog against a Rein and thus learn through the other side that charging the Hog is a bad idea unless you see him hook first. You might see first hand that having no hit scan heroes on your team against a Pharah (or 3^^) is really bad.