According to Mrs. Fan, the Lingnan school emphasizes the use of bright colors to better bring out the contrast.
The philosophy of free flow inherent in the School is perhaps better expressed in the following excerpt from here:

The Lingnan School is characterized by being freer than traditional Chinese painting. It allows the artist to infuse his own feelings, interpretation of subject-matter and emotions into the painting. It does not demand a dogmatic approach in terms of technique or style.
Hopefully you would be able to appreciate that subtleness through my maiden efforts at learning the new style.

