From BlenderWiki
Footage
Use the biggest resolution available for your footage.
Avoid using footage which underwent lossy compression.
Since the tracking currently only use luma (grayscale), it won't track well patterns which only have chroma texture.
Excessive motion blur will affect the accuracy of your track.
As rolling shutter is not corrected yet, avoid fast motions with slow sensors.
Search Window
The search window is the area over which the pattern is searched.
It needs to be at least as big as the marker relative offset between two frames.
Reducing search area is a way to track faster.
Pattern Window
The pattern is the area which is matched between frames.
On high quality footage (with crisp textures), A small pattern will work best (e.g 16 pixels).
Big pattern only helps accurately track large or blurry features.
With unnecessarily large patterns, the tracking will be very slow and fail to track any rotation of the pattern.
