-What guides? Anita Posch website or book
-Where to buy? Highly dependent on jurisdiction. 
-How to store it? Start with Muun or equivalent. Follow up with single sig (+ passphrase) HW wallet. 

A lot of the answers to this poll are North America centric. Having experience trying to do this for family members living in a different country and language presents a lot of challenges/frictions that I took for granted in my local jurisdiction.