you have some good stuff here. My suggestion would be to lock in shadow patterns from the beginning because you are getting things a little mixed up with some of the shadows. Also pay more attention to the relative appearance of edges. As for color you could use more variety with your color choices and maybe mix your greens a little more carefully as some of the scenes the greens are too acid. Greens tend to be shifted towards olive and have a lot more red in them outdoors than people notice.
Yeah - you're just getting started but on the right track so keep at it! The fact that you're working outside really comes across so that is great. There are a couple good books you might want to track down: "Fill Your Paintings with Color and Light", "Carlson's Guide to Landscape Painting", "Alla Prima" by Richard Schmid. Jim Gurney's new "Color and Light" is a must have as well. Keep it up!
What would Caravaggio do?