Maybe perspective lines could help to make it looking better?
Plus, I'm not keen on the chunky pencil lines. Looks a smidge 'doodley' but the designs deserve better than doodles. See here:http://deckplans.00sf.com/Surron/Stinger_Doug_Chiang.jpgOk, we cant all be Feng Zhu and Doug Chiang but they have simple and effective ways of turning sketches into something more substantial. I suggest you buy some quality gray markers (worth the often high price!) and a nice line pen.
I concur. I was about to say this on your battleship drawing. It's really cool as a doodle but it needs that extra layer of detail. I know you are doing one a day, but maybe moving up a next step in detail could really help you improve your already cool designs.