This my first post, so forgive all the possible mistakes and violations of netiquette. I got closer to the world of illustration and concept art during the last semester at my university (i study game design) and took a peek at the huge amount of stuffs available on the internet (tutorials, books, magazines, artists blogs...) and now, finally as it's summer, i got three months of free time to completely dedicate to the subject. no previous art education of any sort except for some pencil drawings my uncle taught me when i was eight (he was a professional painter and now he unfortunately passed away, otherwise i would just stick to him like a vampire). This morning i made some silhouette sketching and found this particularly appealing. The idea is to get a rockish enraged golem out of the shape. It should float with some rocks around the hips and magic energy or whatever. Actually i'm focusing only on values and trying to sculpt the shapes with shadows and light but results were not nice to my eye. I guess color is an harder step i can take later on. The problem is nobody teaches you the very basic things or how the process of digital painting works at every iteration. I can "see" the image inside my silhouette but i don't know how technically pop up the shapes and forms.
What should i do next? keep the outline while filling it with some really dark grey? do i add shadows later just like the highlights? is it better to go from dark parts to lighter ones?