Everyone who has ever mastered a skill knows the importance of practice.  Competence can only be achieved through multiple repetitions, hence the oft repeated advice to paint daily.   I would add that in addition to painting daily, painting mindfully is also critical to improvement.  That is,  applying all your focus and attention to bear on the individual steps that comprise painting.  Everything from the initial designs and sketches, to the colors on your palette, to the value and color mixing, to loading the brush or palette knife, to applying the paint to the canvas must have your full, thoughtful, critical attention in order to make progress.  Painting a scene or subject repeatedly is another way to practice.  It allows you to both acquire skills needed for that particular scene and develop confidence in your ability to execute those skills as needed. It then offers opportunities to expand your horizons asking and answering questions such as “what happens if I change this… color palette, edge, brush stroke, technique, etc“ So, return to the same place again and again.  Paint daily and mindfully.  You will grow your artistic abilities with each repetition.  The creation of art is many things: often hard, sometimes exhilarating, frequently challenging.  For me this is also fun.  However, it’s almost never easy.  Easy is how something feels and appears  AFTER you know how to do it, and as artists, we are often working, exploring and pushing  at the margins of what we know how to do.