I would probably try to bring up the subject of Satanism first. I'd want to make sure they knew what Satanism was all about before I told them I was a Satanist. Hopefully, this way I could at least avoid them jumping to conclusions.
Most of my good friends actually know a good deal about Satanism though. I had a boyfriend a few years ago who was a Satanist, so I started studying what I could about it. I found it all fascinating and constantly annoyed my friends talking about it.
At any rate, I wouldn't just blurt it out. I tried this when I decided to become a Wiccan. While most of my friends didn't even care, (You're a Wiccan now? Wicked...) I had three friends who were very devoted Christians. I knew telling them would be hard, but I'd gone and told everyone else, so at that point I had to, or they'd find out some other way. When I told them they didn't even give me time to explain. For a week they just avoided me, but after that they started doing things. They spray-painted "Devil worshipper" on my door. They spread rumours about me putting curses on other students. They even told my maths teacher I'd cheated on a test by reading their minds. :biglaugh: It was all very funny looking back, but I was really hurt at the time. Eventually, the school called my father, and I had to go home for two weeks because I was "disturbing the learning environment." When I came back, two of the girls apologized and agreed to let me explain my beliefs. Eventually the third girl apologized also. We're all pretty good friends now. I think a lot could have been avoided if they'd just listened to me in the first place though.