Be a Mad Scientist. Be willing to experiment. Do you really want to paint the same thing in the same way your whole life. Some artist do, and are successful. I am not made that way. To me the great joy in painting is Discovery. A new way to paint a familiar scene. If you never experiment, you are not likely to learn anything that you don't already know. Making mistakes is how you grow as an artist. It is part of the process. Don't be afraid to fail.
People have told me, "I can only paint a scene once and I am bored with it." That's because they are only painting what they see. If they paint it again, it will look the same as the first one, because they are only painting what they see. You should be interpreting what you see. Don't paint a scene the way it looks, paint it the way you want it to look. Try different colors than you normally use. Paint it in summer,winter, overcast, hot, hazy. With a Knife, with a different color under painting. Try mixing your colors on the canvas or paper instead of on the palette, the possibilities are endless. You will learn in the process.