you can lower the % for both the Blur and Smudge tool. this will in effect give you more control on how much is "blurred"  or how much the "smudge" is to go before tapering off.

i've used the "cutout" filter to create some of the limited colour range and blended those to create the underlying layer.

as far as i've been able to do, i've yet to find a "simple" solution (that has been acceptable "results-wise") but i have found you can get it down to a routine with a little patience and practice.

hope this helps:)
:)
retrocity