Customer Journey Map / Diagram / Structure

Hi the community,

I'm a little bit lost in the Customer Journey reflexion. I would find some tips, help on how to start the beginin.

I explain : does exists some questions to ask ? Are some rules to respect before mapping ? Do we have to work with paid / earn media in the Diagram ?

If somebody has worked with a pdf which helped him in the past, i'm interested.

Sorry for this message, which looks like a little bit confused but is the case in my head

kind regards dear readers

Ignace