wooow!!! the last one has some good potential! like... some underwater scene or something! I know these are very rough pieces, but may I suggest you try to create interesting moods and atmosphere, by using gradients, layer settings and stuff. the earlyer you do this in your works the sooner you will get a better feeling for the scene you're painting.
I know this motivation issues... but still, never let it keep you from paintig too long!
I had a good weekend and soon will be able to update some sketches again