Start with a close friend or family member. Someone you know who will continue to love and support you, as they could help you in many ways. Best not to tell everyone all at once, unless you want to get it out of the way, nice and quick. If you're nervous or scared about coming out, take it easy. Start with one or two people who are close to your heart. Then slowly expand to a small circle of friends and/or family. And after that, if you feel you're ready, and that you now have the confidence to tell everyone you think should know about your sexuality, then go for it, hun.
As for actually coming out, I've heard many fun, creative ways of doing so. Bake a cake for your friends and/or family and decorate it with the colours of the bisexual flag. Or those one-liners like "This ruler is straight but I'm not.". I even heard of someone who ordered a pizza at a party and told everyone that it's for non-heterosexuals only, and took a big bite. A friend of a friend came out as gay by making a super glittery card with the words "LEGALLY GAY" and a picture of them on it. Another one I heard over the internet was to get everyone to participate in a scavenger hunt, and tell them that whoever wins gets to be the first one to know that you're bi.
I truly wish you all the best in coming out. Good luck and take care!