My main advice would be to pick a single project you care about and commit to exploring it deeply. Every project has its own unique workflow. When starting out, the best loop is to dive deep, zoom out to understand the bigger picture, and then dive back in. While I don't have specific open-source guides to share, I highly recommend reading up on the general Software Development Life Cycle (SDLC). An open-source workflow isn't a special formula, it's simply the SDLC process a specific team decided was best for shipping their software, and it evolves as the project grows.