IBARW: Writing characters with a different background to your own

I was meaning to write this post for ibarw (International Blog Against Racism Week) last year, but other matters got into the way. The advice is still valid - I saw the discussion in Elizabeth Bear's LJ on a similar topic: how do you get around to writing those same characters of colour/ethnicity/religion etc and not commit the same mistakes everyone is chastising commercial media for?

The following is a roadmap of sorts to a character of a different background than your own.

( Disclaimers at the end; non-US-centric )