Hey welcome to the AE! You have some nice stuff there. One thing I'd recommend is getting more consistent facial construction. Some proportions are slightly off and while this is less apparent in your simpler drawngs, the more you trend towards straight realism, the more these small errors become glaringly obvious. If you don't already do it, use a mirror to flip the image, this is a little trick that can make you much more aware of small things that need fixing, such as an eye being a bit low, or the nose being slightly off center and whatnot.
Really focus on guidelines when shooting for photorealism of any kind. I usually spend more time blocking faces out than I do shading them, just to be extra careful.
But you have nice contrast in your drawings, and they're nice and clean. Keep it up man
A 3ds ap eh? not bad at all. Proportions are a tad wonkey but it's nothing crippling. He's got a cool line of action working for him so it makes up for a lot. The colors are nice and clean, and I like how you outlined sections with a darker color of their container, but overall the color selection feels a bit flat. I don't know how limited the 3ds ap is so I can't strike you down too hard in case they only provide like 32 colors or something.
The arwing is porbably the weakest part, mostly because it looks to me like the perspective is a tad off, and the lines could be straighter to make it look more hard surface.
Also, consider your silhouettes when making an action pose. Limbs in the wrong place can be distracting or look weird, even if they're in a place that is technically accurate. Fox's gun is hard to see because it's a similar color to his jacket, and the detail of both objects tangents a bit, making the gun hard to pick out, even if I know it's there. As a rule of thumb, make the pose completely recognizable even in a pure silhouetted form. If you filled your pose with black, does it still make sense? If it does, it's a really good pose.
Hey, not bad. I think your should redraw the mountains too lol. They're probably the weakest part. Also painting water should be more complex than a simple shade of blue. water isn't actually blue at all, but it reflects its surroundings. So the fact that you have a red sky would most likely turn the water a brown hue.