I use. any brush from Photoshop brushes, and for icons I use only the circle brush.
With that I have :
1 - Pressure sensitivity for Shape Dynamics (size)
2 - Pressure sensitivity for Transfer (lighter/darker)
If the brush is not round but some other brush I use Also, in addition to the top settings:
3 - Pen Tilt for the Shape dynamics in the Angle Jitter, for some randomness
4 - Pen tilt for Texture, and leave texture on subtract setting, and play with other sliders.
5 - Some times I use Dual Brush, for additional texture effect.