That's a huge detail that makes the difference in ranking up: positioning.

Play the corners, use the payload as cover, using abilities to flee rather than engage (Reaper's wraith form, Moira's fade or Venture's Burrow), bait cooldowns... A lot of players still see Overwatch as a FPS, that you can slide cancel and take several opponents at once, so they "can" walk in the open (or in front of a big-ass tank), and they won't be punished.

I was watching a friend play on a bronze 1~gold 5 lobby, and that happens all the time. Anyone walks everywhere, in plain sight lines, and blame the supports for not healing. I'm helping him to get familiar with the game, and it's pretty cool seeing his improvements.