She is best to use as a defensive character who had some strong punishes. She does better as an aerial assaulter, and you should really be trying to land a Uair or Bair. You can use Nair if you think Uair or Bair won't land. Her Fair is more of a gimp or quick but big kick, with little KB. Think of her as an easier Zelda. Send them far. Keep them in the air and read will they'll be and/or land. Then send them far away again.
Also, use dat Dair. It has a funky hitbox until you notice that she is using her legs to attack and not her staff. Palutena doesn't have real sweetspots, so even nicking someone with the attack will send them flying downwards.