The first step is to register an email address. Run Tor. Connect to firstname.lastname@example.org via Tor (usually available via SOCKS proxy `localhost:9050`). Make a new account. Use something smart for generating passwords, e.g. https://getvau.lt and always make notes - real notes on paper. Tell someone you trust. Do not tell anyone else.
"I appreciate SDF but it's a general-purpose server and the name doesn't make it obvious that it's about art." - Eugen Rochko