In general this work could benefit a lot from cleaning up. Sorting out the jaggies, getting rid of the dirty textures, and finding a way for the different colors to work together, rather than against each other.

Secondly, you'll need to start thinking more in 3d, and consider your light source. For example the right arm (on the left side) is completely black on the side, yet the right knee which is facing the ground somehow is perfectly visible?

As for your question about the armor plates, I don't know how they connect. The only tip I can give you is to study references. Find videos which show how the mobility work, find pictures which show how the plates are connected. Once you know your subject inside out, it becomes much easier to draw!