Start with high-confidence garden design books, then narrow by subgenre or adjacent topics.
Martha Stewart's Gardening Handbook
Martha Stewart
The Succulents Design Book
Kentaro Kuroda
Dry Gardens
Daniel Nolan
Coastal Gardening in the Pacific Northwest
Carla Albright
The Bee-friendly Garden
Kate Frey, Gretchen LeBuhn
Native Plants for Your Maine Garden
Maureen Heffernan
The Gardens of the Hamptons
Blue Carreon
Edible Forest Gardens, Volume II
Dave Jacke, Eric Toensmeier