@Lucelfo glad you enjoyed the class. I had a blast making it and hope you guys are finding it useful. : )
In terms of going to color, I always do a value study first (like in the video). This helps me establish what is light and what is dark without worrying about color. Then the next step is to do a few color studies (in photoshop). I typically do them right on top of the value study and I do them fairly opaquely because I've never had good luck working transparently there. When I used to do all traditional work, I will just print out my value studies real small and then try out a few color schemes. It REALLY helps to find some other images to use as reference for color and lighting. It takes a lot of the guesswork out of it. Starting from scratch on color with no reference is very difficult in my opinion. I always have something around me- a photo, a few paintings, etc. that sort of hit what I'm going to be going for. I NEVER do a painting without a color study of some sort. Not doing this step always ends with a struggle (in a best case scenario) and a disaster (in a worst case scenario).
Hope that helps some. : )