Welcome to the first tutorial! I really hope you enjoy it and to be helpful ^^
How I work:
When I do the sketches I like to apply the values in a very simple way. So, undestanding where the light comes from and how it is applied to elements is easier.
Also, depending on the complexity, I separate in different layers the sketches, changing the opacity. Thus, the character can stand out against the background.
Original character by @aalmaluar https://www.instagram.com/aalmaluar/?hl=es