As for learning to draw people and pose them? Just decide what you want, find a similar photo, look at it and draw what you see. Really though just "doing it", practicing, makes you better. You don't need specific tricks, just spend time.
Let's say that the design of these "soldiers of the future" is quite good!. The different weapons (infantry kid) along that one with a special weapon and different style gives it a really nice impact to the scene image. If I were too realistic I would say that a soldier would be suffering of carrying those heavy weapons. Ready for "NBQ" battle. Awesome job once again.
You know I really like the Elemental, they are very creative and look very cool. I like that staff, it has a lance of Longinus vibe was that intentional? She/he looks rather bad-ass no matter where the inspiration came from. Good work as always!