transforming a picture to an oil painting

[Eli Aran]

I am desperately looking for a tutorial on how to make a scanned picture
look like a painted work.
with the "Simplifier" filter I only managed to make a picture look like a
"flat" water color sketch
but what I am trying to do is create a birthday gift for my wife using her
picture.
I plan to scan it with very high resolution and enlarge the outcome to a
poster size picture and frame it.
I want to transform her picture to look like a oil painting so I need it to
have relatively thick masses of paint
and I need it to be three dimensional so I want the areas of color to be
bright on one side and dark for shadows on the other.
I am willing to work with layers and masks though I am not too familiar with
using them.
I would highly appreciate if you could please send me a tutorial on this
subject or point me toward a relevant location.
my wife's birthday is December 13. I am not looking for a one-click magical
transformation.
I really want the picture to look like it was thoroughly worked-on and I
want it to really look like a Van Gogh (or any other modern oil painter)
style.
thank you very much for your kind help!
Eli