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you need to organize your linework so it conveys form.. not just on the squashes, and reconsider your color extension throughout all the pieces. color extension is how much of every color you have in a piece like on a pie chart. also, it looks like you drew one picture in photoshop and then applied just a single filter over it... nothing else. Its kinda trite. I'd avoid doing this in the future. photoshop is cool for somethings.. but more often than not you want to avoid filters like the plague.

yeah #2 is best and i also agree about filters....

i think if you want to give it a different look to make it look like a completely diff piece with the same image you could still change it in PS but just not with filters..... or if you do use filters change it mostly with some of the other tools first/as well
that way its more hand altered and it will just look better if you twiddle around yourself smile