So many snippets of inspiration come at you every day. That nice arrangement you just saw in the store window reminds you that purple (salvia) and hot pinks (geramiums) will look great together.
Keeping a dedicated notebook on your desk is the best way to remember what you saw. I use the cell phone camera to save a phrase, a plant, or a botanical name of a plant I like then it gets transferred (then deleted) in my $2.00 lined notebook.
Colors, plants, prices, combinations, etc. - all in one place.
Although I will never have (and frankly would not want) a large waterfall on my property, I made note to place a colorful rock that can be seen where the small water feature splashs in the little pond.
Inspirattion is from whatever you see that pleases you. You can adapt it for your personal pleasure!