Let me give you some tips on drawing this kind of stuff.
First, when drawing humanoids, you should always map out proportions with ellipses before you start filling in any detail. Otherwise, unless you have a lot of experience, you will tend to give your drawings strange proportions. Even if you aren't drawing something realistic, it is VERY helpful to take a look at some anatomy books, to get a better idea of how things are REALLY laid out (rather than how your brain THINKS they are laid out). Also, books on drawing human and animal anatomy usually have quite nice illustrations which you can get techniques from.
(for example, the head on some of those is HUGE)
Second, you should be MUCH more conservative with your strokes. Draw your basic shapes in pencil LIGHTLY (even reduce what you are drawing to simple shapes like ovals, triangles and rectangles), then start attacking the final drawing with PEN. Make fewer, confidant strokes, rather than lots of little sketchy marks. TRUST ME, not only will drawing with small sketchy marks make your illustration look worse, it will make it hard to render in 3d.
Your leg detail drawing is the best of them, because it uses a variety of different strokes. Ideally however, you would get rid of those stray marks in photoshop, since they are distracting.
If you are doing stuff like weapon models (concepts for hard surface models in a non-orthographic or perspective projection), like plan or elevation views, a general rule is that dark shading = further away.
The above stuff doesn't matter very much if you are drawing on a tablet, because you can erase/add detail ad nauseam, aside from the first point.
This is just an example of a drawing I did on the train as a
very quick concept for the new camping rifle, and it's not very detailed, but it gave me a good idea of how I would model it. A good concept would be MUCH cleaner, larger, and more detailed.
Also, for ANY model, at least 1 view is
NECESSARY- the
front elevation (non-perspective, orthographic front view).
From there, an orthographic projection or a perspective projection is useful, as well as a side view.
Hope that helps! And keep up the good work!
