It’s great that you’re focusing on the actual design, which is the most important job a concept artist is supposed to do. Too many misguided aspiring concept artists think it’s about making pretty pictures, so they do these nice looking eye-candy with horribly illogical designs.
With that said, you need to also strengthen your critical foundations in visual art, otherwise, no matter how good your designs are, you won’t be able to compete. Long gone are the days when concept artists can make great designs while having weak drawing/painting ability. Today’s concept artists have to be both excellent designers as well as accomplished artists in general, or else they don’t stand a chance against the ridiculously fierce competition.
You need to really work on your anatomy and figure, because your weakness in that area is the first thing people will notice. The proportions of your figure is totally off (head is tiny, body is huge, arms are short. You should at least sketch out the figure first and then fit the armor suit over the figure, to be sure your figure looks right). There are standard proportion ratios you need to know, and the further you deviate from that basic standard, the more awkward your figure will appear. Make anatomy/figure studies a routine in your artistic development, along with other essential studies like composition, perspective, values, lighting, color theory, etc.
As for the design itself, what’s the point of having tubes on the outside? It’ll be too easy to accidentally sever them when they snag on stuff.
There needs to be more cushioning at the bottom of the shoes, since that’s a lot of extra weight to be carried by flimsy looking shoes.
The shoulder area looks very limiting in terms of range of motion. Many people overlook the fact that the collarbone and shoulder blades move independently from the upper torso, and when designing armor suits, it’s important to allow that independent movement, otherwise you end up with the typical limited action figure toy range of motion (just one socket rotation where the arm attaches to the torso).