Read! Read! Read! Read the good stuff, the bad stuff, read everything you can! Movies! Watch! Watch! Watch! (well, contemporary TV if you must) Old Lone Ranger episodes are easy to find on YouTube as well as seemingly any Spaghetti Western ever shot. Some of the "rips" are about as low res as possible, but some are 720 or even 1080 res (Good!). I recommend "The Traded" for about as gritty for a recent production as any. Not Sam Peckinpah grade violence (thank goodness!), but... anyway. Some have "name" actors, many don't but so what. Lee Van Cleef films are often better than expected (the "bad" in the The Good, The Bad, The Ugly).
IMHO, Tom Selleck appeared in and produced some superior work, even Quigley Down Under, worth chasing down.
Why is something a good whatever? Why is it so bad you'd throw it at a passing car? What do you respond to? What leaves you "no way in h***"? Do not, not, not decide solely on who's in the film or who wrote the book. Decide on the story, of course, but it's the details that count.
Bad news - there are only
The Seven Plots in the world. Bill Shakespeare, Aristophanes, Steven King, Max Brand, that's it. That's the show. But somehow the manga still come out, Romeo and Juliet, Hondo, and It see the light of day. It's how you dress the plots, mix and match them, that counts.
Read! Watch! Write!