Now that I'm completely out of the closet and finally getting my mind together I feel it's time for me to give my advice on the subject.
First bit of advice: Only come out when you're ready. Do not come out if you're still in depression, still desire to be straight or cannot support yourself financially if you feel you'll be kicked out. Also, do not come out to parents or friends if you don't want other people to know you're gay. As it happened with me, I told my parents and they told the entire family. With my friends, one started to hate me and told the entire school. Essentially, make sure you're completely happy with who you are before coming out, and only come out to your friends if you don't care what others think of you.
Second bit of advice: Don't come out during a fight, when you're angry or when your parents are angry.
When I came out to my mom I did the worst thing possible; I told her during a fight. Granted, it was a fight revolving around a gay issue, but I still should have waited until she was calm. She was trying to tell me that the majority of gay people get HIV and I firmly told her that she was wrong. When she asked me how I knew I came out to her.
Looking back, I don't regret coming out to her in this way (mainly because I believe that regret is pointless) but I do wish that I had been a bit more gentle about it. While she was yelling at me, explaining how homosexuality was a choice, I stormed out the house and walked to my friend Kayla's house.
Third bit of advice: Don't get mad at your parents for questioning you or trying to help you.
My parents soon asked me to go see a psychiatrist. I yelled at them when they asked me, which is the wrong thing to do. Go to a counselor if your parents care enough to fork over the cash for it. All the counselor will do is support everything you've been telling your parents and possibly sort out any depression you may be having. You may want to ask your parents to see a counselor as well if they're having a hard time dealing with your sexuality.
Fourth bit of advice: Tread carefully around their stereotypical views.
If your parents are worried about AIDS or disease, kindly explain to them that you will always be careful about what you do privately. Do not, however, go into detail about the type of sex you'll be having if they're disgusted by the idea of gay sex. My parents still are very weird about what they call "the whole anal sex thing", so just avoid that topic all together. If you are a virgin, you may want to tell them that and that you're looking for the right person to rid them of any beliefs about gay promiscuity. If you're not a virgin, you might do well to pretend you are until they're ready to accept your relationships.
Any other stereotypes they may hold are best removed if you prove those stereotypes false by just being yourself.
Fifth bit of advice: If you're attracted to any of your straight friends, don't let them know.
When I came out to my friends the first thing they asked me was if I was attracted to the guys in our group. I lied and said that none of them were "my type" and simply left it at that. Straight guys are much happier believing that you think they're unattractive. It gets rid of the worry that you might want to have sex with them.
Sixth bit of advice: Don't turn into an angry activist at school.
After I came out to my parents I decided to form a GSA at my school. The GSA itself was a good idea, but through it I became an angry gay activist. I fought my way into forming the GSA itself and after that I started writing about gay issues in the school newspaper which got me a TON of negative attention. I'd suggest keeping your sexuality out of newspaper articles if you happen to be on the school newspaper staff.
That's really all of the advice I have for now. If I think of anything else I'll add it here :P