When painting start by working from the back forward. For example paint in the sky. Then paint in a mountain then trees. Combine with foreground lakes, streams, or paths.
Simple ways to get the image you are going to paint on the canvas.
Overlay: You can use an overhead projector and project the image on the canvas and then draw in the lines.
Overlay: I use a different method for an overlay. I go to a copy store and I have them enlarge the subject to fit my canvas. I use a black and white copy for the overlay. I then paint the entire canvas with burnt umber mixed with a small amount of thinner and lay the enlarged copy on the canvas and tape it in place. Then I take a pencil and pressing firmly I trace the main lines. When I remove the overlay it leaves an imprint on the canvas. Let it dry and begin painting.
You can sketch a simple outline of your subject on the canvas. To help you with your sketch you can divide your canvas into quadrants and then divide your photo into quadrants. This will simplify the drawing by allowing you to draw in one section or quadrant at a time. This helps you get the proper angles and sizes correct before you begin painting.