I had a bit of practice with these recently. Had a guy saying that some of the glaze on the plain flat tile was chipping when using a wet cutter, but found a couple of things helped.
TIP 1: If using a wet saw, seal them first with a crackle glaze sealer. This will give a bit of extra bond strength to the glaze and the ceramic base.
TIP 2: Score the tile first with a manual cutter, and run the wet saw blade up against the score line. It may help to slightly enlarge the cut by as little as half a mm and file the last bit down to size using a 100 diamond pad. This score line will act as a stopper and prevent excess chipping on the "good side". This is going to prove pretty tricky on the dados as it will need to be scored at 45 degree angle, but try wet cutting one first with out scoring. If it chips, try scoring it carefully with a pencil scribe.