Let's look at this great portrait of a girl. What caught my eye about this was the colors-red and turquoise. We don't have to do pastels, colored pencils or paint in what colors we think are obvious, we can use different colors from our pallettes. Try it!
Also, check out the measurements. I love doing that. I start with my fingers, my thumb on the portraits chin, my pointer finger on the top of the head, I slide my fingers down to meet, and if the portrait has been done with the eyes in the middle of the head, my fingers will meet right half way down the head.
I am doing an online free drawing class. The teacher actually uses grids and tools to draw portraits so that the drawing is as accurate as possible before any shading is done.