How do you increase celebrity stars?

[Kaye]

Besides opportunities, how do you increase your celebrity level?

[warr2098]

You can by cheating, meeting a celebrity and keep becoming best friends, enemies, best friends,enemies etc with testingcheatsenabled true cheat. Or just befriend them and it increases

[Noodles]

I think showing up at parties when you get an invite also gives you some points, or at least not attending is bad... but I've never been into celebrities so I don't really know.

Here's the guide for celebrity.

[MoMoll]

Impress them, provided you have enough skill level. Invite them to your parties and impress them by having a good party. When YOU invite someone to a prty and it turns out to be a good party, you gain relationships with those you invited.
If, your into it, seduce a celebrity and after kissing and asking to be a boyfriend/girlfriend, your status increases a LOT (often a star). If, you propose your get another star!