I'd been buying some male clothes and had a short haircut before coming out. After working up the courage to come out to my family, I switched to buying ONLY men's clothing and bought a proper binder after using sports bras to flatten my chest for a long time. I came out to my therapist and doctor (if you don't already have a therapist, talk to a doc about getting a referral or find one that you like yourself) and I discussed with her my dysphoria and future plans for medical transition.
Then came the seemingly small yet major things, such as introducing myself as my preferred name to strangers, using the men's restroom in public (for your safety, do this only if you pass as male consistently) and saving up money to change my name.
So, tbh, a good place to start would be to find a therapist and come out if you're in a safe position to do so and haven't done that yet. Then, work on experimenting with your style and doing what you can to pass as male, if that's what you want to do. You don't need need to be on T or even be seeing a therapist to express your gender identity, though seeing a therapist is highly recommended if you want to medically transition (HRT, surgery) or are having any doubts, problems, or are unsure about your identity.