The tutorials here will all be of a technical nature, addressing the underpinnings of all artwork. There are many tutorials out there showing the many techniques, and styles. Styles are a matter of subjective tastes. So I decided to address the technical knowledge that can be viewed as the foundation of good, solid artwork and rendering. These tutorials will cover the basics only. That said - just mastering the basics can lead to great artwork. I am starting with a basic light tutorial series and will follow up with perspective. Below is a good example of an old (never finished) practice (rough) sketch using 2 point perspective, and basic form lighting knowledge, to create an image without references. It is good enough for me to use as reference for making a painting, though reference pictures of armor, elephants, etc. would be looked up to help realize the rendering better.
Remember: No matter what medium you use, whether it is traditional or digital, the technical under pinnings are the same.