hi
im a 15 year old ftm, and im stealth at school. the whole coming out process is long and complicated and tricky, mostly long though, I recommend 1) knowing yourself before talking to your parents/friends, so you know exactly who you are and what you want, especially knowing yourself, so you are confident. Confidence is really important for this. For your friends, if you dress masculine/neutral already, it will be easier for them to accept you possibly, or if you don't, start doing that, so you start to change before telling them ( sort of like proof that you mean what you say ).
You might want to come out at the end of the school year, or during the holidays, so your parents can get their head around it ( takes time, be patient, unfortunately ) or before the holidays for your teachers.
On telling your teachers, you can talk to them after class, or email them something like:
Hi
I am (original name here) and I would like to be called ( preferred name here ) in class, and use these pronouns. I identify as trans/fluid/whatever.
You might also want to talk to your dean/administration if you have one.
I hope this advice helps you, im guessing in my scenario things were easier as I moved cities and identified as male/male uniform at the new school, although without my parents knowing.. youd think theyd tell by the uniform and haircut.... anyway, talking to a counsellor would also be a great idea

:D
good luck
david