A tip? Don't bother with nails and a hammer. I used 3M Command Strips from picture frames, and boy do those things work so well! It's easy to put the frames on the wall, and if you need to remove them, that's easy too! Then you don't have to worry about littering your wall with nail holes that will have to be filled in if you ever re-paint the wall. (Or I guess you could just not re-paint ever, but the Command Strips also mean that you never accidentally hit yourself on the thumb with the hammer.)
I'm so glad that this project is finally done. I literally spent a whole morning shopping for just three more picture frames, and I found some really unique ones at Bed, Bath & Beyond (thank you, coupon) and T.J. Maxx. Normally, I HATE T.J. Maxx, but that store does have some good home goods and scrapbooking supplies for cheap. Can't beat that!