DPS and Tank Suggestions/Tips

so i usually play healers, but now that i've reached gold, i want to be able to be confident in myself when playing at least 1 or 2 dps and tanks. does anyone have some recommendations on dps and tanks i should try to learn, and any suggestions/tips on learning them? for reference, below are the characters i would say i am able to play. when playing dps, sometimes i'll be great, or sometimes i'll go 5-10. i think my main problem when playing dps is aiming, and i've tried using the range simulator thing in practice, and its helped a bit, but it feels like a completely different field in actual games.

healers im great at: cloak and dagger, invisible woman, jeff
healers im decent at: adam, loki, luna, mantis

dps im decent at: scarlet witch, iron man
dps im okay at: star-lord, hawkeye

tanks im okay at: dr strange, the thing