How do I add a book to My Bookshelf & place it on held when it is on somebody's WL?

You need to put your bookshelf on vacation before you post the books if you don't want it to offer it someone.  Then before you take your shelf off vacation hold, put the WL books on individual hold.  This removes them from FIFO and hides them from people looking at your shelf.  Vacation hold keeps your place in line and lets your non wish list books move up the FIFO line so when you come off hold you don't have to start at the end of the line again.

With WL books I just wait to post them until I am ready to mail them. I only like seeing was can actively be requested on my bookshelf.