Its getting better but there is a lot to learn and it can't be done in a few weeks really. I just opened up your shadows a little more on one of your images, I hope you don't mind. I also darkened the sky slightly (though not the way I would normally go about it) just to bring out a little more shape in the clouds. As it looks right now that sky I altered is far too dark along the top and side sections, so ignore that as a finished item. Just look at the land shadowed area on the right to see how a bit more is there to see now. Again this was just quick and dirty and not meant to be a finished change.
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