You need a canvas or whatever medium you choose. I used a burlap canvas that was painted white, from hobby lobby. Then some chipboard letters, right out of my scrapbook stash. And also some craft paint-I used charcoal and mixed it with white to get the shade of gray I wanted. Simply paint the letters, let them dry, arrange them in the order you want, and then hot glue!
My cute hubby liked to tell me that I am his favorite, so I shortened his saying to fit on the board. It looks great on our pretty gray wall. And, it didn't cost me the 40$ plus that ordering a custom sign on etsy runs! Easy as pie!