Coming out is a process. That means that it takes time. In my own experience it took about four years for both my parents to come around completely. Also, remember there will be stages as well. You parents may accept you immediately but have a problem later when you bring home a boy friend. Then there will be your first PDA in front of them. Then there will be the night you stay in one bed in their house. There will be many milestones to cross.
There are times when you have to be a loving child to your parents and times when you should be a tough negotiater. At one point I told my mother that we might never see each other again, she turned around after that. There was one time where I just huged my Father and told him I loved him in his ear. He was better after that.
Siblings can be very helpful dealing with your parents if they are on their side. My sister and brother put a lot of pressure on my parents in the early days not to feak out. If you have a close aunt or uncle who supports you, ask them to speak with your parents. Hearing from their peers can help. My mother's best friend became a great advocate for me with my mom.
Many parents don't want you to be gay out of fear.....fear you will be fired, harassed, murdered, or die of AIDS. In any discussion, you should address these points. Let them know you are safe at your job, accepted by your friends and always practice safe sex.
For the parents who want to be grandparents, if you are interested in having children - then you should also be clear about that. If not, I would not bring it up.
My mother always wants to talk about it and my father never brings it up. But in the end, your parents will always love you, even if they cannot readily show it. If you parents cannot deal with it make the effort to forgive them and tell them this. This is not for them, but by forgiving them, you will lift the burden from yourself.
Always be patient, the TV shows that show the reunited parents and son in 22 minutes are bull shit. Real life is more complex.
My seven hardcore rules:
A. Never come out to your parents when you are financially relying on them - unless you absolutely know it is not going to be a problem. Being put out on the street is never good.
B. Even if you are disowned by your parents, they should know who you are and you should be proud of who you are.
C. Being GAY always means having the ability to develop your own adopted family. Even with the support of my family I have been part of an adopted family of friends (mostly straight) and have found this second family equally rewarding and important to my life.
D. Coming out is a stressful and emotional process - seek the help of family members, friends, even medical advice. If you parents do reject you, you should immediately enroll in therapy with a professional. Talking with a professional will help you deal with the trauma - don't go it alone.
E. If you are having a problem telling your family then talking to a therapist can help emotionally prepare yourself in advance.
E. Just because your parents have gay friends does not mean they will be happy about you being gay - my parents were huge supporters of the gay community but still freaked when I told them.
F. Understand the milestones involved each time your parents see you in a different situation as a gay man.