1. Your focal point is dead centered, which is rather dull as the eye will go there, following the road and then what? It also makes it rather dull and lifeless, try moving it left or right and curving the road accordingly. The c-curve idea with the coast you have is good but the placement of the focal point isn't.
2.This is the secondary focal point I guess, but it's also placed poorly, especially when you take into account the line leading to it, which is leading the eye out of the piece, it's also rather close to the original focal point which makes the image very heavy in this part, with little else going in the rest of it, again, makes for a boring piece. You could try fixing this by moving it to the right after you've moved the original focus point to the left, would create a nice zig-zag motion for the eye to follow, to fix the issue of it leading out of the image, consider some clouds to loop the eye back in or something, but nothing too big.
3. Same as 2 really, the curve is leading into nothingness and away from the main focal point. Again fixed by moving the focal point left (or rather, moving the viewpoint so that the focal point is to the left and the curve of the coast is leading towards it).
4. Isn't really composition as much as it is perspective, the road and the cliffs don't line up when you consider the size of the road, either make the foreground ones bigger or the background ones smaller.