I recommend playing more QP until you get a really good understanding of all the heroes, abilities, maps, healthpack locations etc before playing comp.
Also I suggest to practice 2 or 3 specific heroes until you feel really comfortable with them.
No offense, just an advice. I played comp back then when I hit lvl25 and I got absolutely destroyed bc I didnt know shit about the game^^
Comp is a different world, you won't have a good time if you don't know about the things I posted first.