Try to put the main point of interest in your picture at one of the intersections of the thirds.
Or devide the sky/land line on a 1/3rd 2/3rd ratio. Try to avoid putting the horizon half way down the picture.
[Over The Rainbow – horizon on the lower third, protruding flower is on the horizontal and vertical third intersection]
[Sunrise, Calanais – horizon on the lower third, sun is on the intersection of the horizontal and vertical third]
[Pienza Hillside – high horizon on the upper third]
[Pencils IV – point of focus on the left hand third, but half way up this time]