YAAP 14 and a few questions

I'm a complete newb to installing custom roms on my phone, and I have a few questions for this wonderful community. 1. Where can I find a guide for this? 2. What are some things that can go wrong? 3. Do I need to reset back to Oxygen OS11? Im on 12 right now. If you guys can help me, that would be great 🙏🙏🙏