The people below on the right have lots of knowledge on the skill sets for the majority of the Overwatch heroes
The following setting changes will be able to increase your performance when playing Overwatch:
Having fast sensitivity allows you to be able to quickly react to enemy teamates when your getting shot from behind.
Crosshair information is below this section.
When using a lower brightness, you will be able to see the enemys' outlines easy on brighter maps.
Having your contrast higher then normal will increase the gameplay graphics and colour correction to enable better performance when playing and can help when recording your gameplay.
Since most people don't know, to enable your profile to public is in the account settings from the menu. Having a public profile allows your teamates to check the heroes you play and how good you are with them which can help when your team is seting up a team comp.
While you wait for your queue try playing deathmatch and adjusting your crosshair while you 1v1 other players.
Try test using a small crosshair because it will be better for the long run. You will be able to aim better and have a crosshair that doesn't take up your entire screen.
If you watch streamers that play that hero try using their crosshair because who knows it might work for you.
The following maps will be able to increase your proformence when playing Overwatch:
The workshop codes will be provided below: Some may have more then one code for them. Paste them in the game browser gamemode.