I recently joined a craft group with some friends and we meet once a month at each other's homes. The host chooses a craft and we divide the cost between all of us. In the past we've made "Mom, I'm bored" jars, wristlet keychains, and a perpetual calendar from 4x4 blocks. This month we made photo coasters.
I started by choosing and editing my photos in gimp (a free photo editing program similar to Photoshop). I added a feather border and a quote. I found most of the quotes on-line (some of my favorites are Dr. Seuss).
We bought 4 4x4 inch tiles for the coasters and one 6x6 inch tile for a hot plate. I had an extra coaster that I wanted to redo so I actually had 5. The steps are pretty easy. Modpodge the tile and place the photo on top. Smooth out bumps and let it dry. Then add three coats of Modpodge on top letting each coat dry in between. It will be cloudy but will dry completely clear.
Once the third coat was dry we sprayed them all with a clear acrylic. Be sure to let them dry for 48 hours before using.