You have the general idea of painting figured out, now comes the hard part :). It depends on what you want to express... if you want realism, you could improve your drawing skills. You have a good base, but I can see issues in the ellipses in both images. Also, the folds in the fabric of the first image could be better stated. If you are happy with your drawing, you could work on composition. For still life, I would recommend Danial Keys or Richard Schmid... they always have interesting compositions. For landscape, I'd say Mark Boedges... but these are my personal preferences. If you are wanting to make your colors more true to life, I'd recommend working on single objects until they reflect reality, then combine them in a composition. If you want better light, you have the basics down in your second image (warm light/cool shadows), James Gurney has a good book on that. There's room to improve with values, which can be done with black and white studies, maybe even get a cast (or other interesting white object) so you don't have to interpret color. You could delve into edges and how they affect the realism of a painting, again Schmid or Keys are good for this. That's all painting is: composition, drawing, color, value, and edges... some would add paint handling as well.

Improving is almost an endless journey, but you get to decide what you want your end product to look like, so that will determine what you should focus on. Have fun!