This idea seems very useful to me. Maybe you will like it too! I do mean to give full credit to the creator I am quoting.

Using a grid while painting from life helps you put the model in perspective. Whenever people see that I have a grid on my paper to paint in watercolor, I’m always asked why I do it since I’m painting from nature. I like painting directly without drawing because there is a looseness to it; it’s […]

via How A Grid Can Help When Painting a Live Model — Victoria de los Angeles Olson – Watercolor, Egg Tempera