Honestly depends on what you’re using her for.
If she’s being used as a Vantage unit, then the only thing you can really do is to make sure that she’s getting as much attack as possible (maybe resistance as well because of her Special?). That means making sure that she’s got attack buffs (both visible and invisible).
You can probably have someone like Brave Lucina next to her so that she can proc her Special during every round of combat (providing there’s no Guard effects).
Maybe run someone with Chill Def or a Def Ploy on an ally to try and maximize her damage.
Basically do what you would probably do normally if she didn’t have the attack bane.
This is probably the most important thing, but make sure you know the limits of what she can do. She may be new, but that doesn’t mean she can solve all of the world’s problems, so be aware of that and don’t have her try to Vantage kill everything or she will fail.