Any tips for working Alla Prima

Hi everyone! I ususally work Alla Prima but still feeling like I have a lot to learn. I would appriciate any tips you could offer for working in this manner.

I found this wonderful explanation of how to paint Alla Prima here: http://www.finearttips.com/?p=2386

■ First lay in the darks
Keep the darks thin and transparent
Paint dark to light
Dark = Transparent
Light = Impasto

■ Next build up the lights
Allow the lights to get thick and impasto.
Paint thin to thick
Thin = Transparent
Thick = Impasto

■ Mass in the shapes
For the most part, I start my paintings with massing in the shapes as opposed to a drawing.
This allows my “direct paintings” to stay loose and painterly.
On occasions, I will start with a drawing but, mass is my choice.

■ Value
Establishing value in the very beginning is so important.

■ Focal Point
Generally speaking, I will try to keep my center of interest developed ahead of the rest of the painting at all times.

■ Keep focused
A constant vigil on contrasts and comparisons is made throughout the process.
It’s so easy to go off on a tangent and develop the parameters of the painting but, this can also be the demise of the work as well.

I found this video very educational for Alla Prima and portrait painting: