Nice pieces. You have a good understanding of color and value relationships but you need to work on your brushwork and 3d form. I'm specifically pointing out the overuse of the airbrush tool, if you overuse it, your images can become lost and the shapes don't read well. This would also include relying on "stamp" brushes instead of creating your own shapes and forms. To improve your form and brush work I would recommend doing a mastercopies in either landscape oil painters or digital painters. And try to do the study only using the default hard round brush, your be surprised how much you can learn and get quality images with such a simple brush. A great example of an artist who does this is Devin Korwin. Try focusing on clean shapes and better depictions of 3d planes. Overall, I think you have a lot of skill, just practice placing clean planes to indicate accurate form and work on your brushwork. I kind of showed you what I meant in a paint-over of your campfire, it's rough, but it shows cleaner shapes which in the end will prove a more pleasing picture. Keep on practicing and have a great day.