It depends on your shot (mainly whether or not the shot has a lot of movement), but these are the base settings being used for Strength, our latest short film:

Sample points 3000 (lower setting means faster performance)

Smear Length Multiplier 0.15

Smear Samples 1000

Normal Dilation 0.15

Minimum Motion Threshold 1.0

Squash Bias 0.5

If unsure, apply these and tweak from there!