hi in my opinion i would come out to them in whatever way fells conformable be it a letter or a email or just face to face make it sincere and have confidence. Maybe if your not sure how your parents will fell about it bring up something lgbt related and see how they react hope this helps. i have not came out to my parents yet but this is what i feel is right.
Could you give a little more information, please? I.e. whether you live with your parents, their views on LGBTQ+, etc.
