Something I used to do when I was younger was share books with friends. That, alone, isn’t the tip; my tip is have each person who reads and returns the book to sign your book. They can add comments on what they thought, or just their name, or anything as long as its short.
The first book I had on Wicca was Drawing Down the Moon by Margot Adler. It’s a big book. So whenever I lent it to someone, I asked them to sign their name. It added something special to that particular book.
A day came when someone never returned it. Because that copy was a keepsake, its not as though I could replace it by buying another copy. Now I lend to only people I know their name, address, phone number, and blood type. I will hunt them down to the end of the earth to get my book back.
But I felt it was a nice tip to share with my readers.