Sombra is a hero with high mobility that can go invisible and make use of high ground and teleportation. This video explores her optimal attack range and using the hack and teleporter to have a fast and clear engagement. I have the most kills I've ever had in a game while playing as her after doing some routing.
Key Points-
15 shots to headshot at less than 15 meters
20 shots to bodyshot at less than 15 meters.
About half the damage at 20 meters
At 25 meters its basically an entire click to headshot a static target.
Basic combo. Hack health pack, teleport to high ground, setup teleporter to back line, hack tank, teleport to backline, kill a support then shade out, get health pack.
Alternatively, Hack health pack, walk away for 5 seconds, drop teleporter along 1 path, then engage target along one path then engage from a different angle or path.
Here is a guide about what sombra hacks and emps
Enjoy!