Read more about 4 pro tips for achieving a trad painted look with digital software at CreativeBloq.com
The best thing to do is to try to think (and work) like a traditional painter. Do some research into some of the master artists who inspire you. Try to understand the reasons why they painted the way they did. Learn some of the processes and techniques traditional painters use and try to translate that into digital medium. For instance, when I start a painting, I’ll do a rough sketch and put a neutral brown colour on top using a Multiply layer. This to me simulates an under-painting of yellow ochre or burnt sienna, which is one of the techniques used by oil painters.