Here you will learn how to change your photos into sketch images.
1. Open the image you want to applicate the paint effect on.
Disature your image, by clicking Shift + Ctrl + U or by going to Image -> Adjustements -> Desature
2. Duplicate the layer. Then set the new layer's Blending mode to Color Dodge.
Press Ctrl + I to invert this new layer.
3. Finaly use Motion Blur (some other blur like Gaussian Blur work aswell) Filter -> Blur -> Motion Blur
You can then, try to play with the contrast, try different Blur Filters etc
More Tutorials: 
