Here's my attempt at my brother's back tattoo. Between this and trying to match a few others he had, I was max'd out on layers.
The best tip I came across during this process was creating thin lines from shapes. Using a circle/square (or crescent, if you need a curved line), scale the shape in one axis using the right-thumb stick. Then, global scale down using the D-Pad. This process can be repeated to further scale the line-shape to the desired thickness.