Save your shield bash for purpose of what is presented or potentially possible to happen that can be detrimental to the entire team. Depending on what Heroes are being use.
Moments like stunning Sombra after coming out of her Stealth, reacting to it, knowing they will go for EMP, usually you will be in center.
Shield bash too early could cost you the match or point.
Positioning; Make sure you position that can agroe the team but making it incredibly difficult for the enemy team to attack you, be it high ground, around corners, and behind the Team. Being in the front-line is not always ideal against some hero counters.
Pre-emptive Repair packs, vs Healing, be sure to acknowledge your support healers ult economy, if they need healing, let them heal, sometimes toss them repair pack to negate potential damage coming their way, because if they go down and you don’t have a rally you will most likely lose the match or point.
Be sure keep eye on what enemy team is targeting, sometimes pre-emptive repair pack when you see a specific dps preparing to attack a teammate could mean a difference.
Whip shot, is a anti-escape or denial of access to high ground, at all cost prevent enemy team or dps from holding high ground, if you can boop them off, esp on maps with enviroment kills or off point making them take extra few secs to regroup with their team, ie: Hanamura 2nd point the bridge on main, knocking down say a rein to the lower floor could save the game, letting your team focus on other members of enemy team.
Dueling against Splash, sometimes you need to prepare to block angles of splash damage that can mean a difference of surviving a duel against heroes will aim around your shield. You absolutely must not take any damage from splash, on say from Zarya, Pharah, McCree Flashbang, or even Dynamite.
Using your Shield to body block enemy team heals, on say from Ana, or Bio Nade, and Sleep darts.
Keep in mind, Brig while currently isn’t completely able to handle DPS heroes by herself, she can be against other Supports, sometimes it’s best to go after their support, forcing the enemy team to agro, and prepare to make an escape to buy you time, every seconds counts, if you can force the Healer to reposition or retreat, not allowing Heals to happen, you will potentially and indirectly win the match for your team.
Being Aggressive on Enemy Supports when their Team DPS/Tanks are not focused on you can win you games.
Using your Shield as extension of Reinhardts Shield, Rein’s shield can only go so far, so sometimes you want to block behind him for hacks or pulse bombs or potentially extend his shield length with your shield, prevent incoming damage from going past him, covering entire walkways/pathways to the point.
Sometimes being too close to reinhardt will make it increasingly difficult for your healers to heal the Tanks, so don’t be so close to him, and provide him a shield for when he needs to drop it or retreat to repair his.
Body blocking Ults with Shield in front of your teammates, will be great asset of winning match, though won’t be shown in POTG, but have seen it happen multiple times on streams that indirectly saved the game.
Don’t Shield Bash Genji’s start-up on his Ult, wait for his initial slash, as he is taking damage potentially during this, and can finish him off when he slashes towards your teammates, being near your team can group up, focus on taking him out. Sometimes when you know Genji will go for Supports, or DPS stand behind them so you can pre-emptive repair pack, stun him after his first slash or follow up slash and finish him off. Sometimes you might want to step back a bit, so you can see where he will go and stun him during his recovery.
It’s possible, he will get bubbled on his start-up of Genji’s Blade, since he is most likely calling out for it, worst thing to do is wasting a shield bash on a bubbled target.
You need to bait out Hogs, hook and block it with shield, don’t ever get hooked or pulled in by Grav be it Zarya’s or Orisa’s
Make sure you keep track of Lucio and prevent him at all cost from staying on point with his mobility as you can reach him majority of the time even with Whip shot.
Before the nerfs there was specific damage combos you could do, but in general now you want to melee 3~4 times into combo, sometimes whipshot them first into a inescapeable unblockable situation that is in your favor, say towards a corner forcing them to take few melee hits while passing your direction, melee 5-6 times if they have health buffs/armor and into combo.
Brig is hero who requires predictive planning, and gutsy calls, understanding what is going on with the positions of enemy and teammates, as she has access to 3rd person you can track everyone, the more you play with your gut on what you should do, the better you will be at making aggressive plays that can win you the match. Also be patient, and try your best to be the morale support for your team, Rally voice line gives your teammate hope on snow balling after getting a pick, use it wisely. Use it sparingly sometimes it’s best not to rally, esp. now post-nerf.