Coming out is a VERY touchy subject and task to take.
Phantom is right, it's different for every person, and YOU have to be prepared for the questions that will follow, and provide a solid and Sound reasoning why you are choosing this road.
Some parents are cool with it, some will say "Pack your clothes, your not living under my roof"
Some Friends will say "Cool", Some will fly off the handle and possibly want to do physical harm to you.
I would recommend choosing to tell those whom you feel it important to tell, and refrain from telling others.
So, long story short, tell close family friends, and Don't broadcast it to the world.