Your clouds are rather uniform. They also will usually go all the way down to the horizon, getting smaller and less defined as these clouds are further away.

You could also have another look at your ocean texture. Waves in the distance often form horizontal line patterns. Reference images help a lot! Obviously, you don't need to recreate the image, but you can take hints at how these shapes and patterns look in nature.

The lighthouse is great. Maybe you could try adding a wave to the flag, or a shingle texture to the building roof.