https://docs.google.com/document/d/1pSYR91UiMVKnP3PyvJiCdwRF5wNS_nZzMe-r2WPQUJk/edit?pli=1#

This tutorial covers everything you need to know to start romhacking assuming you are starting as a complete beginner. Most other YT tutorials are outdated and don't represent modern hacking techniques.