Technically they're acceptable; as mentioned some distortion and levelling issues as a result of your shooting position. The exposure is decent, 'though I think a polarizing filter might have given them a little more 'zap'. At the end of the day, there's not a lot to hold the viewer's interest. This sort of image would be fine for an article about the history of the mill; that is as a supplement, but on their own, I don't find them strong enough to hold my attention and interest.
What could you do about this? To be honest, it's hard to say. A lot of times there are subjects that we see that beg to be photographed, but are all but impossible to capture in an interesing way. This is what truly separates the 'shooter' from the 'photographer. Make this an exercise for yourself. Go back and make them interesting. Perhaps a triptych of the sign, close-ups of the brick and rusty textures... things like that.
#2 makes me think of a photo i saw today at the art show. It has potential but i think it is composed wrong. When i look at a water tower that is usually the angle i look at it if i am just walking around and see one. Try to get it from a different perspective. The one i saw today the photographer was almost under it looking more upward at it. I would guess he had the camera pointing almost 75 degrees upward. Try that if you go back there. Also a polarizer would help these shots.
I don't consider crooked lines to be the work of professionals. The verticals need to be made vertical via post processing. That is why I always include extra in my framing to allow for correction and cropping later. Otherwise they are pretty decent
Yeah....not the most interesting.....tiredironkinda said it........I would suggest try to go inside!!! When I first looked at these shots all I thought about was.......whats inside!!
Have fun and go back and play around w/ different angles! Keep shooting!!