Learn how to cut tile with this DIY video tutorial.
If you need to make angular and circular cuts, use an angle grinder and fit a diamond disk. You'll need to fit a continuous diamond disk, not a segmented one, because a segmented disk will chip the tiles. And if you're using an angle grinder, don't forget your personal protection equipment, ear muffs, dust mask, and eye protection.
For more information, including step-by-step instructions on cutting your own tile, take a look at this handy home how-to.