Don’t play her like you used to before her rework.
It’s not her job, place, or capability to press W into the enemy team by herself.
Stick with your team, watch for targets to slap repair packs on, whipshot whenever you can unless you’re waiting for the enemy to engage on you, it triggers inspire.
Don’t use stun for no reason, it has a long enough cooldown that you should save it for key abilities. Roadhog heal, Earthshatter, Coalescence etc. But it is definitely worth using on mobile targets to burst them down with your team. Tracer, Genji, Ball, Monkey, Dva etc.
Use your shield behind cover to use 3rd person view for information, seeing where enemies are. Learn how to shield dance (having shield up, dropping it to swing & immediately bringing it back up). Also try to predict your enemy & when you should just keep swinging vs. shielding if they have an ability that will kill you
You’ll have to figure it out yourself, but there’s a mix of playing in the frontline with your tanks & staying in the mid/backline to peel for supports. There is no 1 or the other, you have to do both depending on the situation and it’s up to you to know when which is better.
You can pretty much take an enemy out of the fight by going for them in a brawl. You draw so much aggro because of your durability & can swing away while surviving with your shield & inspire.
Your #1 goal is to not die. If you live as Brig, your team usually does too.
You should not just be focused on the front line, you should be a space enforcer, looking around for flankers & peeling them off your team with whipshot & shield bash (just be sure not to turn your back to a sniper)
Rally with your team grouped up or it’s not that great of an ultimate. An entire team with 30 armor per second for 10 seconds is pretty nuts. Do not use it to survive ultimates like riptire/gravdrag, use it preemptively to take a fight, not to survive one.
I always keep 1 repair pack on deck unless it’s absolutely needed to keep a teammate alive. You don’t want to burn all 3 packs just to top off teammates at 80% hp. Your healing is gated behind a cooldown, so let your other healer do the work if they can. Sometimes the best thing to do is just trigger inspire & wait