Wanna make a painting of a REAL picture using Photoshop..
Supposing this is the pic.
LAYER VIA COPY (Ctrl+J), name new layer POSTEREDGE
Lets FILTER->ARTISTIC->POSTER EDGES->EDGE THICKNESS, INTENSITY, POSTER EDGES be 10,1,6 respectively.
Highlight original layer and LAYER VIA COPY (Ctrl+J) it again, name this layer CUTOUT
Lets FILTER->ARTISTIC->CUTOUT->No. of LEVELS, EDGE SIMPLICITY, EDGE FIDELITY be 8, 3, 1 respectively.
Now placing POSTEREDGE layer topmost, followed by CUTOUT layer, make POSTEREDGE layer BLEND MODE=DARKEN/LIGHTEN with no change to CUTOUT layer.
We get my final painting (with POSTEREDGE layer BLEND MODE=DARKEN)

We can do a HIGH QUALITY SMART BLUR after MERGING LAYERS for better effect as shown below

An Estella Warren painting got by making POSTEREDGE layer BLEND MODE= LIGHTEN and a HIGH QUALITY SMART BLUR
NOTE:
# Another very good & easy method to convert a picture to a painting is to simply make a layer copy, FIND EDGES filter it, MULTIPLY this layer upon the original layer and HIGH QUALITY SMART BLUR the MERGED LAYERS.
# A HIGH QUALITY SMART BLUR is used everywhere to give a painted feel to the pics. It is the real magic behind these methods, especially the FIND EDGES filter method.
Here's a Beyonce Painting sample of the FIND EDGES method.
WARNING:
There r many methods to do this... most of them by the ARTISTIC FILTERS in Photoshop... but i got my most realistic paintin with this methods.