Tile nippers come in many forms, for most things you need them to be 'carbide tipped, drop forged' and most of them are. There are wheeled ones for glass and geared ones which create more force for cutting, though these are very expensive.
As wih using any tool you should, ideally learn how to use it as if you were going to be using it every day for the next 10 years. That way you learn to use it properly with the least about of effort possible. Here is a short guide on using tile nippers, although this was written for people cutting stone it still applys to cutting other materials too.