The best material for making a tattoo machine is cast iron, instead of stainless steel or any other materials. Many cheap tattoo machines are made smooth and even, with the introductions showing stainless steel, which, actually, is not true, while they are usually made of cast iron by deep processing and rubdown treatment. This information is what you could not see from general product descriptions.
The shader is better build with 10 layers coils, and 8 layers coil for liners. You could not easily tell the former from the latter only by its appearance. However, there may be different in sizes of the coils between the liner and the shader, coils of the shader are usually bigger than that of liner.
Experienced tattoo artists could tell the quality of a tattoo machine from its working sound, whether it is sparking or crisp ringing, to evaluate its potential performing. And also by experience, large capacitive would be better than narrow one but this depends on each machine. You should check and make adjustment in the shop when buying it.
Some professional tattoo machines may get hot in no less than ten minutes after working. When this happens, check the needle to see if it rubs the direct connection. If so, make them separated. Some mini beginner tattoo kits contains DVD to tell you how to tune or set up a tattoo machine, but most of them are copied ones. Or you could ask for the Teaching DVD as a free gift.
