Don't give her space, plain and simple. Stay in that ass! Poking with 5B at a reachable distance is the best thing you could do. His 5B is 8 frames compare to her 5B(11 with the staff, 9 without I believe)Don't get desperate trying to smash buttons if you get caught with one of her combos, the last thing you need is to give her a CH. Just be easy, keep it cool, don't let her Jump forward dash you with her B attack. DP that chick if they trying to run that on you(That doesn't sound right, lol)
I usually turtle against her, and fish for a CH 5B. And when that happens, I'm in that ass! Is all about the Ragna pressure baby! That's my two cents on it.