ALWAYS WEAR EYE PROTECTION AND DUST MASK WHEN USING TILE NIPPERS.
The standard and most used tile nipper is the one with the flat 90° cutting edge. It is generally used to cut and shape the tiles. It is not really suitable for cutting mosaic tiles as these can in many cases shatter the tiles.  Parrot nippers, general nippers are great for enlarging a hole or for getting in some tricky corners. They remove only a fraction of tile compared with the general type but it do the job more effective. These tools can cut their ways into most types of tiles, including porcelain, glass, ceramics, marble and quarry. Parrot nibblers have the cutting end resembling a parrot's beak, hence its name. Other types include a parrot nipper and a mosaic nipper. The parrot nipper or nibbler is very useful for removing a section of tile such as when enlarging a hole or more intricate cuts.
Mosaic nippers have slightly round jaws and give better results. The 20 mm x 20 mm porcelain mosaic tiles tend to cut straighter.
 There are also wheeled nippers which are great for mosaics and I recommend it for using with 20 mm x 20 mm glass or smalti mosaics.
There are other nippers that have other features like the inline cutting nipper, with a slight curvature on the cutting edge which will facilitate cutting curved shapes. Dual use nippers allow you to score the tiles with one side and to split them with the opposite side but will not allow tile shaping. Another set of nippers for mosaic use, has a small bag attached on one side of the jaw. The bag will capture the cut mosaic, reducing lost time wasted in trying to find small pieces that can fly out in the room.
Tip:
Be aware of the nippers pinching the side of your thumb. This often happens if you haven't used this tool before. The inner side of the thumb in your holding hand, can get pinched by the spring retainer. Many tilers I know (including myself), have all been receiving this little bite from the tool. If you get pinched once, it is very unlikely that you'll get pinched again... the next time you will pay more attention on using the tool. ;-) Cutting and trimming circle shapes on thick or tough tiles can be challenging and time consuming.
It pays if you first use a wet cutter or saw with a diamond blade at the bottom.
Tip:
Cut straight lines as close as possible to the marking. The diamond blade will be cutting deeper at the bottom section of the tile than the top. Now, start using the tile nipper to trim the marking and finish the job with a tile file. | 
