Have a small group of transgender and queer friends has helped a lot, especially early on when I really needed someone to bounce ideas off of.
My incredibly supportive cisgender partner, who identifies as mostly gay and demisexual, has been with me since only a few months after coming out. In a conversation where I was describing some of the medical elements of transition, he saw that I was nervous about his perception of me changing for the worse. So, he told me “Why would I have any issues with my boyfriend becoming actively more attractive to me over time?” He has stuck to that and been a source of constant affirmation and euphoria ever since.
Of course, the help of medical transition is hard to overstate. I have been on testosterone for about 10 months now and it has been a huge part of why I am able to see myself moving forward through life as a man.