Matt Kohr has been painting for a long time. He's the real deal.
He also has downloadable lessons that are super affordable, if you're looking to improve your skills or just getting started.
I've used his courses myself to get a grasp on digital painting techniques. Most courses are out of my reach, financially, but Matt's are grouped into sections and are only $10 a piece. You get Photoshop files and instructional videos and even some brushes.
But enough from me! Check out his site ctrlpaint.com for all his demos. He also uploads free lessons on his Vimeo channel every Thursday. (Disclosure: I have no affiliation with Matt Kohr whatsoever. I'm just a happy customer!)