I am getting pretty good at snakes from my area. There is a FB group called KY snake identification. It is one of my fav groups. People will post a pic of a snake and you can try to guess it on your own before reading the comments.
You are correct about location. It really is key. For instance we only have 4 venomous snakes in our area. Cottonmouth, copperhead, timber rattler and pygmy rattler. Knowing your venomous snakes and their ranges in your area really helps to narrow things down. For instance Cottonmouths are only far western KY with small pockets here and there. Timbers are really only East and pockets around Brown County IN. Pygmies are far eastern hilly KY. So really the only venomous ones that we have to worry about in my immediate area is the copperhead. They are very distinct. So if you know that you are not looking at a copperhead then you can be fairly certain that you are not looking at a venomous snake. Of course this differs greatly for area. Especially desert areas like @UglyBob. there are about 6,548 species of rattlesnakes out there!