There are literally hundreds of different router bits or cutters available. In many cases, the differences between the shapes that they produce is small- and with many, the only difference is in the size of the cut. It is not necessary to own a huge number of cutters to be able to do most jobs; you can add to your collection as and when you need a special cutter for a particular purpose.
Many cutters are available either as high speed steel (HSS) or as tungsten carbide tipped (TCT). TCT cutters last many times longer than their HSS counterparts, but are more expensive to buy in the first place.
On the other hand, no cutters are cheap and there is little point in spending a lot on a cutter that you may not use very often. A good compromise is to buy TCT cutters only if you know that you will use them a great deal, or if you want to use them on hard materials such as laminate or chipboard.
If you are careful and make sure that you can form the correct angles, you may be able to sharpen HSS bits yourself; but TCT cutters can only be resharpened by the manufacturer or by a specialist sharpening service. Remember that although poor cutting is usually a sign of a worn bit, it could also be due to a worn collet—and broken bits are often due to worn collets as well. Clean out collets whenever you change bits, and check the marks on the shank of the cutter; if they are rough and patchy, rather than smooth and continuous, the chances are that the collet is worn and should be replaced.
A final point to note when buying cutters is that the collets of most routers will only accept a single shank size, although some can be adjusted like an electric drill to accept other sizes. The majority of DIY routers accept a shank of 6mm, but this is something that you should check in advance.
As with all power tools, there are a number of essential precautions that should be adhered to at all times. In addition, however, you will find when using a router that it has a tendency to pull out of control if you try to push it the wrong way through the wood. It is very important, therefore, that you learn always to push the router in the correct direction, and to make sure that the workpiece is firmly secured.
Routers produce quite a lot of dust and woodchips. so it is sensible to wear both a face mask and goggles at all times.