Assess the work you did in class this week.
Having made an exploratory study of one or the other of these images, there are at least a couple of things you'd like to do more effectively. Probably more like several things. Before you launch into another try at your image, I recommend identifying specifically what needs refinement. It may be that your questions can be answered by working out each issue on a piece of practice paper, one at a time.
Let's say, for example, that you painted the landscape (from Joshua Tree National Park), and the foreground pinnacles didn't separate enough from the background. Now is the time to ask which variable(s) could be working harder to pull the rocks forward and push the ridge back in the illusory space. Go down the list:
Color: Is there sufficient color difference between the shapes? The warm/cool dynamic is pronounced in the photo, but it could still be exaggerated, if that would help.
Value: Maybe you swallowed up too much of that important light on the left-facing sides of the rock, or could you afford to darken the ridge a bit? Both?
Ask about wetness and composition in a similar way, one variable at a time. Try out your potential solutions as isolated passages on scrap paper, one at a time, until you are quite sure you're ready to make another version of the painting.
The reason for limiting how much you're trying to improve at any given time is to avoid confusion.If you take on everything in general, odds are you won't be able to keep them all in mind at once. If you focus on one at a time, however, you will see definitely see some improvement. Guaranteed.