Shadows can work but you need to think about where to put them in the frame, in your composition. I've had a shadow be the subject. This to me is a little too wide, with too much space on both sides. I think this could go a number of ways - the fence and the shadow, the shadow and the orange tree that stands out to the left, etc.
Something to me looks a little off. I know it was late day but the color almost looks too saturated or... Or maybe it was the focus/depth of field. Probably losing light late day I'd try to use a smaller aperture to get shots of the entire scene - the fence, shadow, tree line - all in focus. Then as the light's going and I need to use a larger aperture (to get more light into the camera) I'd probably go with just the tree and the shadow, or part of the fence and the shadow. I find that time of day I have to work quick before the light's gone.
Try walking/roaming around a little and looking thru the viewfinder and think about where things are in the frame til you get something that looks like it will make for a good picture. Think about your vantage point and perspective.
And listen to Gary, he knows his stuff.
Now I have to say I'm not sure if I exactly pre-visualize, although that's a valid way of composing images. For me it's more like I see a shot and know that's it, that's the shot. Or not. lol That's when I don't take the shot and keep looking til I see what I know is the photo I want.