I wholeheartedly agree! Acquire books for the taxa you are most interested in, or are most likely to make observations of. Then get a range of books, if you can, relating to your location. Especially for the taxa that are large and complicated, with many genera, and many species in each (such as insects.)
The more broad guides (such as for a country or continent) can be really good overviews for learning about families or genera, while the local or regional ones can be more helpful for getting down to species level.
My big thing has always been wildflowers, so I have quite a collection of books, ranging from more general to more specific. I have field guides to wildflowers of North America, of Northeastern United States, of New England, and of Vermont and several other states.
Whatever type of guides you have, pore over them to learn what the important characteristics are that distinguish species. This can help you take better photos for IDing. For example, for wildflowers you may need to see the blossom (arrangement, size, number of petals) the stem (hairy or smooth) the sepals (size and position) the leaves (arrangement, veining, the undersides); and still you might not be able to ID below genus level. Who knew there were so many difficult-to-identify Asters in New England?
Guidebooks that describe the species, in addition to simply having photos or illustrations, are often the most helpful for distinguishing species that are similar. And counter-intuitively, books with illustrations can be more useful than books with photos, because a good scientific illustration will show all those distinguishing features that might not be visible in a photo.
As far as where to find guidebooks, in my experience you are unlikely to find many in a (public) library. If you still have independent bookstores in your area, they will often have, or can get, good field-guides for the region. And I have found excellent books at National and State Parks, and Non-profit Nature Centers. Garden centers and stores that sell bird-feeders and birdseed sometimes have decent guides to birds, flowers, butterflies, even bees.
When I travel, my favorite souvenir is often a guidebook or two, even if I may never return to that place. But why, I wonder, did I buy Fishes of Hawaii all those decades ago? I didn’t even go snorkeling…