When thinking about art it is best to sketch what you see, paint what you see and create what you want to create.
What does sketching what you see actually mean? Instead of focusing on the whole picture, look at the objects and draw the lines that are there, the shapes that are there. Simplicity can be key when starting a sketch.
Then when you start to paint, look at the shadows and what colors that are within those shadows. Black shadows are basic, look for any hint of blue, purple and even red. Those simple touches of color in a watercolor painting can add a new vibrance to your paintings.
And of course paint what you subjects that you like to paint. It makes it more fun, art should be enjoyable.