If you are playing as a front liner and Seris casts her ultimate, you can put down your shield and prevent yourself and your teammates getting pulled in, and at the same time making her waste her ult.
When Makoa is stunned, aim a bit lower on him to hit his head hitbox. Once you learn the location of his stunned head hitbox you'll see it's very easy to output high damage on him during his being stunned.
When Drogoz is airborne, try snapping almost directly in an upward direction then snapping to his location horizontally. I do this when playing and seem to easily headshot him mid-air on a regular basis. example: https://youtu.be/DGVWJDimNv4?t=83
Right before Andro's Reversal shuts off you can send your fully charged shot at him (easy to headshot him when he's trying to position for Reversal) and hit him before the green things are gone. Pay attention to the sound of his Reversal.
When sniping an Evie who is about to leave Ice Block, aim a little bit in front of her path in the direction she's facing because she will usually blink after leaving the block and tends to walk forward a bit first.