How to Cut Tile
How you cut tile will depend largely upon the type of tile and its thickness, as well as the shape of the area to be cut. For thick tile, especially marble tile, it is best to use an electric tile saw. This looks a lot like a table saw with a water reservoir beneath it that keeps the saw-blade cool as it grinds its way with its diamond-hard edges through the dense tile. These saws operate much like a table saw. Simply draw a line on the tile where you wish to make the cut, lay it on the table and feed it past the blade using a guide. Be sure to feed it fairly slowly, and also be sure to wear goggles in case there happen to be any flying chips.
For thinner tile, a manual tile cutter will do. These are basically a device that makes a straight score down the tile and then puts pressure on the tile so that it breaks evenly along the score. These are much less expensive than an electric tile saw (also less mess).
With both of these tools, you will only be able to make straight cuts, and with the manual cutter, you will have to make cuts completely across the surface of a tile from edge to edge. This means for rounded seams or unusual shapes you will likely have to resort to tile nippers. These are like a pair of pliers with rabbit teeth. The nippers break off a little bit of tile at a time. If possible, first score a line to indicate the area to be removed. This will help keep the nippers from breaking off too much, which is all too easy to do. So don't get in a rush as you nip.
For holes in the tile itself, you can get a special bit for your drill.
As tough as tile is, it is also brittle. Too much pressure here or there will cause a break and ruin the tile. Thus it is always wise to be judicious with pressure. Always begin with minimal pressure and slowly increase it when nipping or cutting. After some practice, and a few broken tiles, you will get the hang of it.