When to declare emergencies?

[SamTDS]

xwhitemousex wrote:
Guess the rule is "better safe than sorry" and just declare on everything.

Hopefully the penalty points for making an incorrect emergency call isn't too severe...

Currently flying my (amazing) PA-46 Malibu Mirage, and for a fresh pilot like me it has a lot of things to monitor compared to the Cessna and small Pipers.
Then again,
when I fly the PA-46 I feel like I'm in a 747.

The penalty is serve. I had a bad add on plane that I thought had failure so I declared an emergency and it penalized me like hell!