There are two schools of thought on creating an under drawing before painting.
The first school is that the creation of a drawn guide for paint placement is essential for accuracy.
The second school of thought is that an under drawing isn't necessary and may even impede freedom of expression.
I'm firmly in the first school of thought, having been trained in classical drawing and painting and feel that these have benefited me to observe and translate shapes and values accurately.
My current painting on the easel is a bit ambitious in complexity. Its worthwhile throwing a challenge at yourself now and then to push outside the comfort zone and make yourself sit up and pay attention. I've drawn it freehand as I do with nearly all my work. The top right hand side has been altered just a little to reduce the size of the fish as its out of proportion with the others.
I created a speeded up clip of some of the drawing process. I'm busy fighting with the learning curve for a new video editing program and this video is not fabulous quality, but you can see a little of my thought process as I draw perhaps.
The painting is 24" x 24" on gessoed masonite. I like this surface more and more for painting.