Before dark came...

First of all i must say that you have great sense of depth which shows in this image perfectly. You also capture colors very well.
Lighting is nice, also composition and color palete (makes really great mood).
Brushes you've used for sky rocks and sea are almost perfect.
All that kinda bother me is the shape/rendering of those rocks in foreground. I would make edges more sharp and use hard brush for rendering. I usually use lasso tool for selection and then render shadow or lighting so there is some clear edge.
What i would suggest you is rendering a lot of rocks from photos.

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pa še enkrat... dobr premisl glede šole.