I feel the best option for me is to get players on GAF to practice with me, to see how they can help me improve.
For Lucio, I always try to stay close to my team in the back line behind them, in order to provide the necessary health buffs, but I will speed boost back to the center for protection If I ever get flanked. If my team gets destroyed and I survive, I'll head back to the spawn room to use Speed Boost+Amp It Up to get them back into the fight.
In Zenyatta's case, I have a bad habit of overextending, which leads me to a quick, painful death. I need to space him out more effectively, so that I won't get squashed or singled out by the opposing team.
Zarya is a weird case, as I know how to time her particle barriers, but I never know when to use her main beam or grenade launcher during her ultimate. Her grenades do more damage, right?
I try to play more aggressively with D.Va, but that tends me to go kaboom more times then I care to admit. Ganking and harassing is her bread and butter, but enemy players seem to know how to telegraph what I do beforehand.