If you're already using Biotic Grasp, press Orb and it will summon an orb of the same type quickly.
Use healing orb about 5 seconds before you attack 2CP/payload, straight vertical so it bounces up and down. It will heal any initial poke and the orb will be off cooldown quickly.
Hack cancels your Ult, so use it when Sombra is dead or zap her to stop the hack (if you must). Also, Symmetra can lock-on, outdo your self heals and kill you. Stay away with your high movement speed or zap her to death (if you must)
Use heal orb to conserve healing. Don't fire point blank, move away for max sticking time.
Right click at about half healing meter in team fights to refuel without being forced to 1v1/only attack.
Keep your other healers alive, top priority! They make your own healing last much longer.
If you get Coalescence quickly, use it to break chokepoints and attack through shields with team support. The enemy will probably not have ultimates yet and can't stop you.
Dying refills the healing meter (don't know about being ressed) so if you think you're going to die, use it generously to save others.
If your team is trapped in Grav and you have Zen/Lucio, STAY. Let them Ult and you will survive most of the time. If not, Fade out, Heal orb + Ult your team. This will work against standard attacks and enemy EMP but not anti-heal or most offensive ultimates (Genji is single target and your Ultimate will outheal him). It can be better to die and start the next fight with a coordinated Coalescence push.