It would be easier to do iso if you used a smaller sprite hieght/width. Imo, they seem kinda overly simplified, and er, bad, based on what I have seen from you.
The grass looks a bit messy, and random, and could use better form inside the tile
The guy with red hair has two lightsources, one from the hair, and one on the rest of the body.
The lineart seem kinda rough on the shrunken version, and the shoes seem to have a really basic shape.
You could use some more contrast on the skin.
If the designs/style isnt yours, then you can probably ignore this :X