The WL has to be public. Just go to it and click on Post This Book. It will be offered to that person. You will get a credit. (You can look at my WL and see what I mean. Feel free to post a book to me!)

Make sure that you are on their wish list page.  They cannot be on vacation hold.  It does not work if you are on the book details page, such as if you when through their wish list to the book page.

It will be on the top of the confirmation that you are posting to such a person.  

If they are on vacation hold, it will go FIFO.  If it rolls over, it will go FIFO.

They do not have to be a friend. 

From the Help Center:

 Can I post a book directly to someone's Wish List?

Yes.  If you have a book that is on someone's personal Wish List, then all you need to do to offer that book directly to that member (and NOT to the first person on the Wish List) is to go to the member's Wish List and click the button there.  Be sure the ISBN on your book matches the ISBN on her Wish List!

• Your book will be offered to that member first, no matter where she is in the Wish List for that book.
• If that member does not request the book, it will then be offered to the first person on the wish list and continue to be offered until someone requests it or until it is Posted into the general library.

Both you and the person you are posting to should not have their bookshelf on Vacation Hold. Make sure to use the Post This Book button on the right of the screen while on their Wish List and not any other posting buttons or it will go to FIFO. If you do it correctly, you should see message saying you are posting the book to that member on the screen. I always recommend talking to the person before doing so in case they don't have the credits to accept the offer and get bumped off of the Wish List line because of it or they have RCs that you might not be able to meet. When you post this way you will get credit.

If you use the Mail to a Friend option, that is not the same as posting a book to someone and it will not earn you a credit.

Yuppers, those three answers cover your question nicely !

Thanks for the info. I was trying to figure out how that worked and you answered all my questions.

You should make sure it's OK with them first. Some people have to carefully plan credits and if they're further down the list on that one-it may put them in a bind as far as credits go.

Another good point.  I used to try posting multiples to people, thinking they would be happy to receive several wishlisted books and I could save on shipping.  As often as not, the requester doesn't accept both....then the books are redirected to FIFO.  Whenever possible, it's best to ask first....JIC the other member is out of town, overwhelmed by Mt. TBR, or short on credits.

I'm a fairly firm believer in FIFO, though there are forum cuts via the "Is This On Your Wishlist" threads but I can wait out a book.

You'll still be sharing your books with people with similar tastes doing it the FIFO way.

Gail