How do you reserve a book you bought especially for a buddy?

If it's posted on their Wish List then post it directly to their personal list.

I don't know if it's on their list, and I don't know how to do that.

Go to their profile & click on their wish list. Then you find the book you have & click "post ths book".

Or are you trying to use the mail to a friend option? If the books is not wishlisted, you can post it on your shelf and click mail to a friend, it will walk you through the steps to print the wrapper. If the book is wishlisted by any member, (you can check by adding it to your wishlist and hovering your cursor over the exclaimation mark) then dont post it on your bookshelf because it will be offered to the first person in line for it.

To see if there are any copies of the book listed or on any WL's before posting the book, add it to your Reminder List. This will allow you to see if there are any posted, then if it shows 0, click on the title (being sure you have posted the book BY THE ISBN NOT THE TITLE) and you can then see if anyone is wishing for it.

If someone other than your friend is wishing for it, you need to make sure that your friend adds the EXACT SAME ISBN as your edition of the book, and then as Cheryl said, go to their WL and use the "post this book" button there. It will tell you on the next page whether you are posting it to your friend's WL or not (upper right corner of the information box there states "you are posting this book to xxx's WL"

But, if it has other copies in the system, you will have to use the "send to a buddy option"

Hope that adds to what Cheryl & Erin gave you :)

If it's a WL book that you want to send to a friend w/o getting a credit: post a dummy book that has lots of copies available (think John Grisham, James Patterson etc...,). Then mail that one to a friend.  Be sure to check the weight of your book before adding postage so you have the correct amount.