Tips for going solo in competitive?

I don't have many friends to play with and the ones I do have different schedules than I so I'm stuck doing solo comp. What are some tips for me? I played 3 comp matches and got cooked on each. And my teammates kept getting disconnected.

I main tank but hop on healer if needed. I usually play Thor, Magneto, Dr Strange, Invisible Woman, Jeff, or Rocket.