This seems like as good a place as any to park this policy while I'm thinking about it. I mean, I know I need to start a FAQ page, and about eleventy other things. (Which doesn't even count the personal stuff, like take my dogs to the groomer and do something about my hair.)
Following and Friending: Okay, this isn't so much a policy as the way it seems to be shaking out due to my general distraction. (I'm not an absent minded person, I just have a LOT to try and keep track of.)
Twitter: I don't automatically follow back, but I do generally answer mentions (with an @ so I'll see it). And if you reply to or mention me, the chances go up I'll follow you. I usually follow readers, other writers, book bloggers/reviewers, librarians and other book people. And also @russellcrowe and @nathanfillion.
But let's face it, if you compliment my books and don't try and sell me something or get me to visit your site to see your sexxxy pictures, chances are, I'll follow you back. I'm easy that way. (But not any other way.)
Facebook: If I'm pretty sure you are a reader (or a book person as mentioned above), I'll friend people on my FB page until I run out of spots. If you're not obviously my audience (i.e., young adult and generally female) it helps if you drop me a message along with the friend request telling me you're a reader, or that we met at a writer's conference, or we're in YARWA together. But make sure you "like" my writer page, too. One, because I need people to like me to bolster my self image. And two, that's where I (try to) post updates about signings, appearances, new book news, etc.
Now I have to think about what else to put on a FAQ page. Other than: "Will there be a Splendo(u)r Falls sequel?"