The usual software wasn't doing it for me because the effects looked very fake, so I explored further and found the free FotoSketcher. Its focus is purely on such effects - and it's brilliant. I particularly like the Painitng 5 (watercolour) and Painting 6 (oil) effects - they are very realistic.
Then it struck me - what if I applied these filters to fractal images? The results, in my opinion, are fantastic! Enjoy .... and do try it yourself!