What weapon are you using? My preferred strategy is to make sure I have lots of room behind me to back away, and bait her attacks where she drops her head down, then punish that. Some of her attacks have her flail her arms around a bit and then she drops her head down, some don't, usually just stay back until you
know the head's coming down, get one good hit (or two if a fast enough weapons, almost never three though) on the head, and repeat. At some point you'll get a visceral for sure.
A weapon with a good
vertical hit is helpful. Because if your timing isn't perfect, you might whiff with a smaller-ranged weapon, but with, say, Ludwig's transformed L2, you can still catch the head even as it's being raised again.
The last phase where she tears off her arms and spams the jump, however, is kind of a crapshoot.
If you have strong ranged attacks like a cannon (+ bone marrow ash) or arcane spells, you can stay back and finish her off with it sometimes, but that's not always possible.