Great start! really like your concepts. Bit rough, except the battleships, veeeery nice detailing on those!
Show us more of your more detailed stuff
Hope you dont mind a paintover of your form studies. Check the perspective on your box, the perspective lines on top converge in front of the box instead of behind it. It visually translates to a box that grows smaller as its reaches the viewer.
Check the horizontal planes of a cube in perspective, you will notice that the plane closest to the horizon line is more skewed(eh, smaller because you are almost looking at it in profile). - The same should apply to your cylinder. (So the circle on the bottom should be less eccentric than the top, if the top is closer to the horizon line).
If the cylinder was meant to be in the same perspective as the box, it would have to be even less eccentric at the bottom than what I did.
For a short intro to perspective I can recommend Loomis' Successful drawing, although each page takes a while to decipher its definitely worth the read
Cool stuff you got here Although as you mentioned in your latest update the readability is lacking in some of them, you might want to push the contrasts further in some of them and might define your forms more.
Remember to lay in big blocks first and make sure it reads, usually a picture should read at 30 feet distance within 30 min keep it up!