2 Red Flags
I was reading this piece (again) by one of my favourite people actually, Derick Sivers, he has actually written a book on it. He has a rule of thumb that I find useful when asked to join a new project.
It has to be either a 'hell yeah!' or it's a no.
In other words, when a project comes across your desk and it's a kinda cool one, then it's a no (or it should be, I struggle to get this right). Something has to be gripping and exciting or it just going to end up being a distraction filling up my calendar.
2nd red flag, which ties into the first, is when I catch myself saying.. 'but the money is good.'
That's not a good reason to do something.
Do things for good reasons, at least most of the time (sometimes we also just need to pay the bills) ;)
Pierre