I've found Orisa to be an interesting one. And I love her. I've got as many hours on her IN QP as my schedule will allow, and haven't taken her to comp yet but I plan to.

She should stay farther back. Maybe a mid point between the front and the support is ideal, mainly because she's projectile based so aiming is easier from far away. One thing I've noticed though is people don't use that fusion cannon to its full potential.

The cannon has 150 bullets before having to reload. I'll say that again to emphasize. 150 bullets before reloading. This means she can effectively shoot for about 12 seconds before stopping. That's a long time.

Orisa makes space by laying down suppressing fire. She makes it so it's a dumb idea to turn that corner because there are green bullets flying all over the place. I've found she makes space best while laying down suppressive fire and moving her shield up whenever she can.

What I mean by this is well, this: throw your shield up front and start shooting through it. You'll probably drop someone out of place. Bonus points if it was a support. Once the opposition has backed up a little, throw that shield farther out while moving forward with your team and keep shooting.

Really, never stop shooting. It's actually a mind game against the other team, "when will suppressing fire be done?" That's the point though, as a good Orisa it's never done