When I joined Tumblr: Early 2011
# of followers: 14,000+
How I believe Tumblr has helped my career: It was was the main catalyst in getting my name out there. I can post music or answer questions from fans, and it gives a sense of my personality to them. It's also not a bad place to advertise anything else I'm involved in.
My advice for artists on Tumblr: I've just always posted my original content for the most part, and it seems to have worked out alright.