If I can throw you a hint or two...Use FSSkyworld clouds, they're superb. Don't use stratus, they're typically useless and unrealistic. Don't be afraid to make multiple layers of the same type of clouds. Cirrus always look the best at dawn. Try to avoid small puffs of cloud. Try as well to avoid hard looking horizontal lines at horizon levels(bottom of your cloud set.) Try not to have your cloud composition too "busy", avoid creating too many different looking cloud styles in the same pic. Best one I can give is put cumulus above and below you in one piece so you get right inside the cloud cover. You can slew or pan around to position them, but if you start off right in the middle of them you should create some very dramatic shots.Love the last shot btw...
