Coming out, I assume, would be a lot easier than people think.
People are very tolerant in this age and fortunately we all have friends who like us for who we are, not out sexual preference. If you are gay, they will learn to accept it. It's seen as a characteristic by a lot of people, just the same as whether people think you're funny or charismatic. It's really nothing to worry about! I have a couple of friends who are gay and everyone who knows them seems completely relaxed around them. There's no hetero-homosexual tension or anything.
Personally, I wouldn't go around telling everyone. Just the people you trust, and the people you are closest to. I'm talking about your best friends here, and the people you hang around with outside of school/college/work.
Coming out to your family can be much more difficult, I imagine. If you want my advice; just come out with it. Your family obviously will love you no matter what, and they will accept it. You'll feel better for getting it off your chest and it might even help your relationships with friends and family!
Best of luck.