I say everybody, because you never know who you're going to connect with, who they're connected to, and how you can help each other.
A big mistake people make is to judge people by their appearance. This isn't junior high. A guy in a plaid shirt, with pocket protector, and glasses could very well be a Simpsons writer. The flashy guy with the designer clothes, expensive sunglasses, and fancy car, could be a wanna-be in debt.
Another reason to know everyone is because people in other classifications may know people who can hire you. Because they're not in direct competition with you, they're more likely to give you referrals and make introductions.
There are certainly strategies when you want to get specific with who your target (the people who can most directly get you where you want to be the fastest). For all other times, be open to the people you meet, searching for people with like-minded sensibilities.
For more tips and articles by top entertainment industry coach, The Greenlight Coach, visit www.theGreenlightCoachBlog.com