Finishing the edges
All of our tiles have a slightly rounded upper edge; the glaze (the glass-like finish that carries the design) curves over this edge a bit, but it doesn't go down the side of the tile.
This means that if you have the edges of tiles visible (either at the end of a run of tiles, or on a corner) you'll see a rather untidy area where the edge of the glaze and the naked ceramic body of the tile meet.
One solution to making this area look tidy and finished is to use either a slim 'pencil' or 'border' tile alongside the pattern tiles - these are glazed on three sides so they provide a tidy end point and help to frame your lovely pattern tiles.
They are often simple long thin rectangular tiles (usually called pencil tiles), but they also come in 'quarter round', 'bullnose' and lots of other shapes and designs.
There's a good selection here to give you some ideas.
The other option to cover raw edges is tile trim. This is a metal or plastic strip that has a perforated flat section that is bedded into the tile adhesive under the last tile in the row, with an upstanding section that covers the raw edge of the tiles.
Tile trim comes in lots of different colours, profiles and thicknesses - it's worth checking the depth of your tiles before purchasing as a 'too deep' tile strip will stick up above the tile surface, and a 'too shallow' one won't completely cover the tile edge.
Tile strip is quick and easy to install; you just cut the length you need and butt sections up against each other as you go. Around windows, corners and ledges you may need a mitre saw to cut sections where they need to join neatly at an angle.
Once your tiles and tile strip are installed, and your tile adhesive is dry, you grout the joins at the same time as you grout the rest of the tiles - the end result is a tidy and professional edge to your tiles.
There's a good selection (in the UK) at Topps Tiles.