Just harvested this info with the Sims 3 Package Editor. The following traits improve performance quality, which would improve rewards:
Social Butterfly (20%), Ambitious (20%), Natural Born Performer (30%) for Magician
Diva (20%), Social Butterfly (10%), Ambitious (10%), Natural Born Performer (30%), Charismatic (10%), Virtuoso (25%) for Singer
Athletic (20%), Ambitious (10%), Natural Born Performer (30%) for Acrobat
Absent-Minded, Clumsy, Coward, and Loser all reduce performance by 20% for all 3 performers.
The Profession Simoleon Booster LTR would boost cash, while Entrepreneurial Mindset would help you gain levels faster. Since they're professions, they work with this Ambitions feature - So EA has been OK at tying these things together