Using Ana's nade can boost all sources of healing and that includes health packs and the payload's passive healing which you can use to your advantage.
You should take advantage of Hero-specific custom settings that can change how some abilities work or interact. For example, tweaking Mercy's settings can allow you to "super jump" which is an essential part of her kit.
Symmetra's Teleporter can only be damaged at its base, which is something you can take advantage of against Ashe's BOB and Torbjorn's Turrets.
You can use emotes to go into third-person and look around walls. While it can be considered unfair in some games, Overwatch has left the mechanic in since its 2016 release.
The payload and robot from Push mode cannot be contested if you are invisible or invulnerable so don't bother using something like Zenyatta's Transcendence or Mei's Ice Block to contest the payload when attacking. You can still bodyblock them to stop enemies from pushing.