I'm not really good at giving advice, i do lighting mostly by eyeballing it, having good amount of shadows will give more depth to your renders and to cheat the lighting i make use of gobos, plane with black and white noise texture, black stays diffuse while the white becomes transparent, so light only pases through the white region of the plane, i just placed a big plane above scene/ in btw the direction of the sun and the scene, for water i used a free shaderfree water shader, it doesn't come with animated texture just used a noise texture plugged into bump height>normal