Don't face Strix head on. Pouncing head first may result in a (skilled) Strix sniping you up close, if caught in his scope. Sneak behind him and lower his HP with your knives. Once he knows you are there, pounce on him to finish him before he hides.

Maeve will try to sneak up to you. You should always be aware of where she is. Your Flare will help you. Otherwise, if she is not behind cover and you can see her, shoot her.

You can also try to quick-scope and shoot her. Just remember where the crosshair is nearly located.