Fortunately, you don't have to understand all the details. However, there ARE a few points to understand.
Continuous potential is inaccurate at such a low value.
You can still make interesting images from those types, though, so don't avoid them. Some folks like the effect. Generally this should be set to one less than the number of colors, i.e. usually 255. If it is too high, the range of colors in the picture will be much less than those available. There is no easy way to predict in advance what this value should be.