I have a little book called Second Steps by Caroline Mornement - she also publishes the Craft Galleries Guides
It is a handy little book , gives you pointers about pricing, approaching galleries , wholesale versus sale or return etc. Quite a handy little book to refer to. There may be a more recent version .
When I first started out I bought a book called Running A Workshop basic business for craftspeople ,by the CraftsCouncil. If it has been updated (mine was '85) that would be a good book too.
Most information is now available online , if you know what you are looking for - it wasn’t an option when I started out