Coming out is very individual and it depends on many different factors. Without more information it's a bit hard to say what to do. However, our coming out section has a wealth of information as well as the wiki page. I will say I am financially dependent on my family right now and I came out. without going into my saga, it is on the coming out section. It's been tense for me, but not all is bad and it's progressively improving. And many others who happen to be in the same boat have had positive experiences.
What kind of doctor? Endocrinologist? If that's the case, I suggest looking up trans friendly endos. There are lists of them online and surely there will be someone within your reach. You could also contact you local lgbt center and see if they have more information. Keep in mind, most will not prescribe hormones without an hrt letter from a therapist. You can find therapist the same way as endcrinologists. And there is always the possibility of starting through informed consent.
I understand this is all scary, but I suggest she come and post here. Everyone here is very friendly and we will all try and help her the best way possible. If she is afraid of posting, she can always contact me through pm. Having said that, talking with others is a great first step to develop the courage and confidence needed to come out