For hair and makeup, YouTube will be a great resource. Multiple people have recorded tutorials for styling her bangs, as well as interpreting her makeup.
Hair Tutorial by MsMMena
Makeup tutorial by MakeupByMelby
Subsequently, you can look up tutorials on how to make your eyes bigger, like Ariel's, and pair that with a red lip.
I would recommend posting in the Disney forums regarding her dress and props, as the cosplayers there collectively have the most experience doing Disney costumes and outfits. Hope some of this helps!