Chore chart for tasks and behavior; busy, regular schedules; plus lots and lots of activity/exercise helps. Stress balls and fidget spinners, and get two of everything because we lose stuff all the time.
If she has trouble reading and comprehending, try having her listen to an audio version while she reads from a book or e-reader. Watch her diet for red dyes. Be prepared to switch gears often, use timers (the old fashioned crank ones so she can easily see how much time is left) for tasks be it homework, household chores, or behavior goals. Switch things up often: 15 minutes of homework, then 10 minutes of running around outside, then 15 minutes of homework, then washing dishes, then 15 minutes of homework etc….
My ex and I used to take turns redirecting our son to his homework problems in the he early grades so we could alternate getting him back on track with taking walks outside fir us to calm down, though ODD also made him complain-y & stubborn.
Work with a mental and behavioral therapist.
Recommend anything by Sari Solden— she works with women and girls with ADHD because it can present so differently than in boys. Also read the book “You mean I’m not lazy, stupid or crazy?”
We don’t mean to be annoying, forgetful and unfocused: we’re just wired differently.
When talking to her, get to her level, look her in the eye, hold her hand, arm, face, or touch her in some way to get her attention. Then make sure she focuses on you and have her take a few deep breaths before you deliver whatever it is you want to say. Also write it down to help her remember.
Talk to her teachers, the school counselor, any coaches, and get an IEP and whatever other services the school offers.