Working on a commission piece and figured I'd post a snapshot of the process I do for clients who do not have predefined character designs.
First pass is based off of written descriptions and visual elements/inspirations only. Usually, for this pass, I just do chest up, as getting faces right is most important and outfit revision can be caught in the initial sketch pass.
The second pass is after the designs have been looked at. I update my own notes, change anything on the designs that's easy to fix, and leave that open in a tab to reference as I begin cleaning up the initial pose sketch.