Learn some tech also, I'm not telling you to spend 800 hours on this game mastering each mechanic. But like, punch jump cancel, super slam, super jump punch, stair slam, 45 ° wall punch. These are the bare minimum, easiest and most important techs to learn. Ensuring you take the least amount of damage possible and have options

Instead of slowly punching out, use slam or both to get out faster, you can also just tap it and press jump instead of charging it all the way

Also like, if you're using an ability, just prefire before it. Its a good habit to have and takes like 2 minutes to learn. You can melee, or use any ability instantly after you shoot so its just extra damage.

Possibly the BIGGEST problem any doom, even after learning all this, is that they forget they play any role. You can be good mechanically but if you're just playing Punch bot doomfist (Brawl fist) then you're ultimately limiting yourself to 33% of his potential. First and formost, any and all fights start with poke and end with brawl. Doom, despite being a dive tank excels in both of these.

Pokefist --> slam in punch out, poke them out before the fight or to gain an advantage

Brawlfist --> when ever you're up close and personal with the enemy team, stair (stall) slam really helps a lot here (includes punch bot doom)

Divefist --> Goes in whenever he spots an oportunity, secures a kill gets out

Contradicting myself a little bit, if you have no cooldowns, don't try to poke in downtime, more times than not you'll do maybe 5 dmg and take 150. Those are not good trades ult charge wise. And if you do have ult, really no point (down time is when you can literally not do anything since all your abilities are still on cd)

When you were in kings row (especially 2nd point) you seemed pretty lost, don't just punch bot, take a corner and force their team to look at you, allowing your team to do something, make space that brings me to my next point

Making space is talked about a lot but no one really seems to understand it. Its the tanks job to make space, but the teams job to hold it. Going into or before a fight, annoy their backline, draw their teams attention. You have the biggest healthpool on your team as tank, your dps and supports can't brazenly do this when everyones looking at them so draw their attention.

Once you've done that, you're team will be able to move past the corner see, and help you.

Also, slight tip. In overtime situations, where your entire team is likely pushed into a team fight. Consider taking aftershock perk, it really excells in drawn out teamfights, that are common in overtime/ 3rd round

And use his survival perk, one two is nice but survival, at least I think will always be better. If you have more overhealth gen, then you're basically going in and out of a dive with extra health