You haven't even told us what kind of film and meter you're using or what the general atmospheric conditions are. We don't even know if you're talking about black and white film (seemingly), color neg, or slide film. Unless you have a spotmeter which can read specific sections of the scene, try to find something gray or medium green corresponding to average metering and just expose for that. It's hard
to give a crash course over the web per the extremes of the scene in the shadows or highlights without knowing any specifics. You can also alter the scene via filtration for black and white film if necessary. If the trees in the foreground are dark green conifers, for example, you could use a red filter to darken them. But this will also make details in the background as well as clouds more resolved and dramatic, since red wavelengths cut through atmosphere better. On the other hand, a deep blue filter will darken the greens while making atmospheric things in the background much lighter, much like 19th century blue-sensitive emulsions. Any deep filter will obviously require significantly more exposure based on its filter factor.
