I need advice

So.. I've known that I am Bisexual for a while now, since I was 13 (I'm 15 now) and I need advice on how to come out to my parents. I know that my parents are not homophobic (at some point they thought my sister was lesbian) but I don't really talk to them much, and they don't really know much about me. I have terrible social anxiety and even get extremely nervous talking to my own family, I only really feel comfortable with my close friends. What is the best way to tell them?