Two books: THE CREATIVE PHOTOGRAPHER and ON PHOTOGRAPHY
Thank You
I don't think a new piece of gear will make my photography significantly better, at this point. I do think that moving from a d90 to a d500 made a big difference. The AF system on the d500 is just so much better, along with the image quality. My "captive audience" (wife) said "wow, even the crummy ones look pretty good...."
Two lenses have made a big difference to me, a 300mm f4 pf and a 500mm f5.6 pf. Thats because I'm a hiker. A big heavy lens just didn't work well for me.
I'm learning a lot from using old glass from my Nikon FG and F days. I have a Micro-NIKKOR 55mm f removed link I'm enjoying a lot. I think I'd like a 105mm. I'm also using a few other old lenses. They make me deliberate more.
The main thing is to get out and have fun...field skills will make the biggest difference. But I could use a 2nd body so I'm not changing lenses so much.
@alanb191 The old Nikon 105/2.5 is very nice (I have one of the later "gauss" type ones in a converted pre-AI version) and will render things beautifully, but on an APS camera it's a little on the long side for some uses, while not tele enough for wildlife, and not close-focusing enough for macro. If you craved one back in film days, you may be better off with an 85 now. If you like the length, consider the later 105/2.8 Micro, because its close focusing makes it a grand lens for chasing bugs and butterflies and the like, and it's still good at normal distances too.
On DX the old 55 Micro is also a great lens for shooting the small end of nature.
If you like to play with old lenses and want a bit of exercise, consider looking for the ancient 200/F4. This goes back to near the beginning of F days. By modern standards it's no great shakes on sharpness, and it does not focus close. And the earliest ones are a bear to convert to AI because the rear flanges don't come off readily...BUT...they don't mind extension tubes. I have one that more or less permanently lives with a 68 mm. stack of extensions, which makes it a macro at a good distance, though focusing is a real challenge. You will miss about 49 of every 50 shots, but when you hit it right, there's something about it. It's full of magical Nikon pixies or something.