Hi Jarmo, I dropped by your Deviant SB (but could not find a function that allowed you to post comments except through signing up)
You have a broad range of skills and photography. And your art style currently lends well to a graphic (hard b&W contrast) style that can become distinctive. Depending on what you want to paint/draw. I can suggest drawing people, objects and vehicles and buildings as shapes of black
So, if you want to improve - say your character drawing - try casting or imaginign a hars light on someone's profile and block in only hard black shapes. It will help yoru brain understand 3D shapes as well.
of course, soft pencil shadings and studies will help improve these better!. G luck!
Wacom Evangelist - Europe