Formal:
* Bonne chance, Anne. (This is the most common and neutral way to say "good luck".)
Informal:
* Bon courage, Anne. (This is a more encouraging way to say "good luck" and means "good courage".)
* Tout le meilleur, Anne. (This means "all the best" and is a more informal way to say "good luck".)
You can also use a more specific phrase depending on the situation, such as:
* Bonne chance pour ton examen! (Good luck for your exam!)
* Bonne chance pour ton entretien! (Good luck for your interview!)
* Bonne chance pour ton spectacle! (Good luck for your performance!)
Remember to always address Anne by her name to make it more personal.