If a painting has been inspired by a scene or photograph or visual memory, most of the work is likely to be focused on arranging the shapes and colors to mimic the vision you began with. Like this one, for instance:
Early last winter I was driving toward town one evening when I looked to the west and saw an unusually brilliant sunset. For the most part where I live there are almost no places to pull off the road, and much too much traffic to stop in the middle of it, but I was fortunate to be right close to a small dirt area on the edge of a Christmas tree farm, so I was able to park my car, walk a few yards and take photos of the beautiful evening light. I had to change very little from the photo to the painting. Looking at this now, the two small tree clumps on the left look too dark. Oh well, always something to fix.
I enjoy trying to make good landscapes from photos I take. It gives me a chance to work on my color mixing and brush skills. Copying from reality has a built-in feedback mechanism—if the painting looks like (or better than) the photo, then you did a good job, and if it doesn't, then you get to see where you need work. If the painting works as a whole, then you made a good composition as well, either in the photo or when you translated it into the painting. If you're lucky, you get a lovely record of a scene that means something to you, and a way to share something you love with others.
At my stage, this kind of work is mostly about building skills. I am sooooo learning the basics right now, but this painting felt like a major advancement for me because of the way I approached it. I recently borrowed a painting dvd from the local library called "Painting Mood and Atmosphere in Oils" by Carolyn Lewis. In it, she took a plein air sketch and a reference photo and created a studio painting from them of a sunset beach scene. I am still trying to develop a consistent and efficient approach to painting, and the guidelines she gave made a lot of sense to me. I really liked the way she worked and the colors she chose. I decided to take my sunset photo and use her steps to turn it into a painting. For me the biggest change was to mark off the large shapes and masses in the sketch, and start by blocking each one in with a single color, on a peach-tinted canvas. When you've completed that important step, then you know whether your composition is going to work or not. Only then did she go through one section at a time, working in the secondary hues and rough shaping. The last step was to apply the fine details and to correct any problems in one section at a time. Even though her demo was in oils and she was working constantly into wet paint, her basic approach worked just as well for me in acrylics.
I kept replaying her dvd over the three days it took me to finish the painting. I still didn't feel like I'd seen it enough times, so I ended up ordering a copy from Amazon. I look forward to seeing it again. They also have her companion book by the same title, and it's on special right now. The book goes over the same principles with many more example landscapes, but I really recommend the dvd. Maybe your library will have it.