If you have my sims trophies you can enable the playful emotional aura and do 3 playful paintings.
I think the girl sitting on the rocketship in paintings gives the flirty aura. Just enable it.
If you have the sims 3 reward lamps you can buy confident, playful, etc and enable each of those auras.
Fishing can put you in the confident mood.
Flirting makes you flirty (lol).
Telling jokes can put the sim in a playful mood.
Take a steamy shower. (flirty)
Bubble bath (playful).