This chapter contains rules of thumb: advice and guidelines. Each of them has a catchy title in hopes that remember it as a slogan. Many people have the intuition that if two dimensions (2D) are good, three dimensions (3D) must be better--after all, we live in a 3D world. However, there are many difficulties in visually encoding information with the third spatial dimension, depth, which has important differences from the two planar dimensions. A crucial point when interpreting the channel rankings is that the spatial position channels apply only to planar spatial position, not arbitrary 3D position. Vertical and horizontal position is combined into the shared category of planar because the differences between the updowns and side-to-side axes are relatively subtle. The psychophysical power law exponents for accuracy are different for depth position judgements in 3D than for planar position judgements in 2D.