B.O.B. I've just gone through this thread and you have some great pixeling work here. But I see two things that affect every bit of your art:
1. You put too much detail into everything, making it hard to tell what things. It overwhelms the eye with detail.
2. Some scenes are so busy that the eye doesn't know where to look, foregrounds and backgrounds merge together. Different areas have the same colours, contrast or satuation.
As an experiment could you please draw something very simple without any real details. Then shrink it down by 400% and see if it is still easily recognisable and looks good. If not, work on the large version again until the small version looks great too.
I think that would help. I hope this proves useful, I wish I had your skills!