I go to local nature areas, and if I see a plant I don’t know, I use the iNaturalist app to identify it. I usually try to plants I’ve seen growing in local nature areas, and I usually choose plants I see growing in dry areas–not plants I see mostly in washes or along stream banks.
I look at how plants are growing together–what’s growing next to what, and what’s growing under or intertwined with what. I look for repetition, or plants that tend to grow in groups of themselves, too.
I try to get a feel for what tends to grow together, but I also look for color and texture and shape combinations that I especially like. Then I bring those ideas back to the garden.