I like to know that I'm working with good people, that the standards are high, but I also want to know what it will do for me as a performer. So, some things I ask are:
In what ways is the character going to challenge and develop me?
Do I like the script/project as a whole?
Is it paid and if so on what scale?
Where is it being performed/screened?
Is it likely that potential employers are going to see it?
Can I use it for showreel?
Will it look good on my CV?