There's a guide! It's here: https://docs.fedoraproject.org/en-US/project/join/ (or: https://fedoramagazine.org/how-to-contribute-to-fedora/)

Personally I feel a good way to get involved is to test updates in bodhi for those packages you care about, or to take part in the process that happens around release time where we go through several freeze cycles and have 'blocker bugs' that need their fixes to be validated: https://fedoraproject.org/wiki/QA:SOP_blocker_bug_process

I would recommend to look at Fefora's infra "backlog": https://forge.fedoraproject.org/infra/tickets/issues