It depends on what your setting your shader for. Color? Black and grey? Smooth black and gray?
If your doing regular black and gray or using color, a long stroke, large gap between front spring and the armature bar. For soft shading and highlights, it would be the opposite and with a little more tension on the rear spring. The springs on a liner and shader differ in the sense of how fast the contact screw comes in contact with the spring. Are you apprenticing? Obviously not, or I would suggest asking whoever is teaching you. In order to be sufficient at tattooing you need to understand the fundamental basics of the machine and practice, practice, practice and study. If your truly adamant about learning the trade, invest some money in lots of books. And/or get a job as an apprentice at your local shop.
There are so many things about the machine you can't learn on the computer or through books, only at a shop. If you wanna learn the secrets and not just how it's put together, make it happen by exploring education and teaching possibilities via a experienced artist.