You need to have the 5 following things to start with:
- something to glue your tiles/tesserae onto (a base),
- tiles/tesserae (or cut tiles),
- glue that will work with both your tiles and your base,
- something to cut your tiles into tesserae with, and
- grout
Everything else is just variations on that theme. It helps a great deal to have a project or design in mind and starting out simple is MUCH better.
- Base: For a wood base you can use MDF, fiberboard, or hardboard and seal it well with a water-based wood primer. (I tend to avoid most plywood because the water in the glue and/or grout can cause them to warp.) Terra cotta pots also make a nice starting project. These too need to be sealed if you want to use them for planting stuff in.
Other materials can be used for a base so long as they are rigid and durable. Be sure to clean them thoroughly to remove any grease, dirt, or oils.
Primers: For wood any water-based wood primer will work. This is a paint product and is different from deck sealant.
You can also make your own primer for wood or terra cotta with a solution of 5 parts water to 1 part WeldBond, applied in several coats allowing each coat to dry before applying the next.
- Tiles/Tesserae: Decide here if you want to work with broken dishes, stained glass, or glass tiles. Ceramic is easier to get hold of but a little harder to work with (IMHO). Stained glass needs a couple more tools to cut it, but it's easy to get and relatively inexpensive. Glass tiles are the easiest to work with, but can be the hardest to get and more expensive.
- Glue: If you're working on wood you can use just about any thick water-based glues--tacky glue, WeldBond, Crafter's Pick, etc. If you're working with china, the thicker the glue the better. Ceramic tile mastic, silicone, or Liquid Nails is good here because it allows you to build up the adhesive behind the thinner tiles to alleviate the differences in thickness.
- Cutting tool: I recommend a dual wheel cutter when students are working with glass. They tend to be the most versatile and the easiest to learn to master. Nippers are fine if that's all you can get hold of, but they can be harder to work with when you're just starting out. The dual wheel cutters can generally be found at stained glass shops and some hobby stores.
If you’re using ceramic items (tiles, plates, etc.) as tesserae you can break them into manageable piece by wrapping it in a towel and whacking at it with a hammer. Then cut them into smaller shapes with a nipper or cutter.
- Grout: Start with dry, sanded grout. Premixed is hard to work with and more expensive; avoid it at this stage unless you want to make your life more difficult. Sanded grout is very forgiving. All you do is put some in a plastic cup or bowl, add water a little at a time and stir until it's somewhere between the consistency of mayonnaise and canned frosting. If you’re working with unsanded grout you want something the consistency of peanut butter or a little thinner. Follow the directions on the label to apply or go to any book on mosaics for pictures.
Before grouting make sure that there is no adhesive on the face of the tesserae or more than halfway up the side of the tesserae.
Tesserae placement: When laying tesserae keep in mind the space your grout will need. When using sanded grout, the spacing between the tesserae should be between 1/8 and 1/2 inch, basically no thinner than a craft stick and no thicker than your pinky. When using unsanded grout the space between tesserae should be 1/8 inch or less.