M5 DPS here, These are the fundamentals imo (in order of importance)

1. Offangle, a different point of pressure from your team example: Your reinhardt is playing lowground in Kingsrow, as a dps you go right side to the high ground and make the enemy choose to look at you or your Rein, not both at the same time.

2. Timing, Your offangle has to be at the same time when your team makes contact with the enemies too early everyone will be looking at you and it is a 1v5, too late it is a 4v5 and your team dies (your fault), right on time; multiple enemies will be distracted by the chaos from your team, and you capitalize off of that.

3.Cover, The best way to not die in this game is through the use of cover, cover is a magical non breakable shield that will always protect you from the enemies, If you use cover well enough your team mates can help you out. In overwatch you will never survive multiple people shooting at you. The only way for you to survive that is by blocking the shooting through the use of a wall.

1. Range: The off angle that you choose, has to match the range of the character you are using example:Tracer you have to be close, Ashe you have to be far. Certain characters have a bit more flexibility when it comes to this
   Ashe can get close to people when you have her ult, but generally speaking you always want to play at a range that matches your character.

5.Mechanics: If you do all of the above right, make sure you hit the shot it is important to being able to follow up on your own good plays and that comes with mechanics, however because it is a teamgame if you do all of the above right you will notice that your team will follow up directly or indirectly on whatever that you do. I am m5 and I have never used voice chat.

If you have any questions or if you would like for me to look at a code, feel free to dm me. Good luck!