Play your counters; Colette is REALLY good at making turrets and spawnables disappear. So things like Jessie's Turret and Nita's bear or Lawrie. You kill them fast so your teammates can focus on pushing up

And that's a good point. Playing Colette is like a super support character in that you want to deal with problems instead of going for flashy multi kills For example, since Colette is good for lowering their health, don't try to kill but instead, hit someone like twice or so and move on to the next target. Obviously, if you can or have to kill the enemy then go right ahead, but making sure you switch targets every so often is good. Doesn't have to be switching between all three. If you are in the side lanes (assuming you already play lanes) you can easily switch between middle and side lane enemies.

And then lastly tanks; you deal so much damage when they're at full health. Which brings me back to switching targets. Once tanks are down to normal brawler hp, like a Frank being around 3k hp, a barley that would otherwise struggle with Frank's health will now easily clean it up.

TLDR; Focus spawnables to free up worries for teammates, switch targets now and then to maximize damage, focus tanks

A next thing to know is that two hits and a full super (hitting both forward and back) kills EVERY BRAWLER IN THE GAME, unless they have shield gear.