When I make tiles, I usually stamp them with StazOn and then color. If you are stamping with StazOn, my understanding is that they do NOT need to be baked, but it is an added precaution.
I would stamp it, let it dry, color as desired, bake and then spray with a sealant. Make sure if you are going to bake them, you do so before putting the cork on the bottom. LOL! Don't ask!
I have colored the tiles with chalk and also with StazOn on a q-tip. They have both turned out nicely.
I always get my tiles at Lowes, but you can also get them at any home improvement store like Home Depot, etc. You can also buy sheets of tiles at Lowes. One word of caution if you are going to be making magnets. The only magnet I have found that is strong enough to hold the tiles on the refrigetator are also sold at Lowes. They are circles and are GREAT! The ones from WalMart do NOT hold the tiles up. They slide right down the refrigerator. Again, don't ask! LOL!
Hope that helps you out!
- Susan
www.inkedblessings.stampinup.net