Hitchhiker's guide: iPhone to Android

This summer I'll buy my first Android phone (Moto X? Nexus 4? Who knows..) and I've always been an iPhone guy.
So, that's the question: if I want to sync all my things (music, videos, contacts, and so on) from iCloud to Google services, what are, in your opinion, the "must-have" steps I should do?

I'd like to create here a sort of guide for all the iOS people that want to switch to the "dark side". :D

Thank you!