Foregrounds are hard to find or have been for me at least. I have been trying to apply the rules etc, but i get lost in the moment when i find something i think looks good. Iam enjoying it all non the less.
Make the effort. Remember - photography is the knack of turning perspective into art. Finding foreground is often simply a matter of getting on the ground: As an artist, the object of invoking perspective is to place the audience in the viewpoint you have chosen. When you omit foreground, you are saying "there is something far away, distant and remote from you." When you instead put it up to your feet: You are saying "you stand before a vista. Look." The waterfall images you've got are great. Personal preference only, I only go B&W when the coloration is heinously boring AND the texture really pops. And, if you're going to go B&W, crank the shit out of the contrast in Lightroom so that you can really see it. But that's just my take on it. Anybody can teach you how to take pictures. Nobody can teach you how to take your pictures.