The following tip is from Belgian artist, Pol Ledant:
At the age of Forty I decided to leave the business life I was leading and I tried doing some watercolors.
First I copied many paintings, because you have to learn different techniques.
I soon understand that I would be limited, if I didn't learn to draw. So I took drawing lessons.
After that, one of the best-known painters in Belgium, who lives nearby, advised me to paint with oil. I looked at him painting for hours and what I mostly learned is "don't be afraid to put color on to the white canvas you have before your eyes. You'll run all those colors later."
The most important thing is to acquire you personal way of painting, people have to recognize you without being obliged to look at your signature.
From that moment on, you'll start selling your paintings.
Best wishes to everybody