So I was doing a warm up sketch before I got into commission work and with a bit of playing around I finally figured out how to use the 'linear dodge (add)' overlay to its proper effect. Its use has always escaped me in the past ^^; but I have always thought the effect looks just incredible.
So yeah just from a daily practice sketch, I was able to tinker and figure it out, always learning more as I practice, the practice is real guys :P

LEFT IS WITHOUT THE LINEAR DODGE EFFECT, RIGHT IS THE LIGHTING WITH LINEAR DODGE EFFECT


PROS to the linear dodge add effect:
- more realistic and dramatic lighting
- brings out highlights in colour better
- can be used well for setting in atmosphere (such as sunny day, gloomy night lighting effects)
- glowies if need be
- great tool for speed painting

CONS to the linear dodge add effect:
- looses some detail
- need to be careful with the amount of applies colour (else can wash out/ make whiter)
- too much looks too much :/
- needs to be used selectively within logical lighting areas
- need to use logical colours for more realistic looks