Engraving is similar to the other hand graphic arts but it just takes longer to learn to run your pencil or paintbrush (graver).  After that is mastered it is artwork of deciding what to paint.  A book to look for is called "Art of Engraving" by James Meeks. Try a search for it at www.Amazon.com  There is another book to look for called "Engraving on Precious metals"  Try Amazon for it too.  Also there is another book by the same name "Art of Engraving" but written long before the Meeks book that is available for viewing on line.  For fine artistic examples of hand engraving and other metal working methods the book Art and Design in Modern Folders is recommended.