Read somewhere 70% of all photos are taken with a smartphone. They are why point and shoot cameras are becoming a thing of the past.
13x19 fits the same aspect ratio as a full frame and 13’’ is the max of a lot of printers. I show a lot of 13x19 prints in 18x24 frames.
I tend to go with the best you can afford. You will up grade less often.
Look for a good camera club. A great way too get started. In the San Francisco area where I am there are lots of clubs. Northern California Council of Camera Clubs for example. A great source for learning and meeting people.
Work you did looks great. A rule of thumb is not to have the horizon dead center. Not a big deal with this picture but you might keep it in mind in the future. Rules are made to be broken so don't over think it. It's what you like that matters.
The lens that you use is the main reason you don't capture what you see. A longer focal length lens tends to compress the depth of field that we see a shorter lens, a wide-angle tends to expand the depth of field that we see. A standard lens on the camera such as a 50 mm on a full frame or a 36 mm on a crop sensor give the most natural looking depth to an image. What's considered a standard lens varies with the size of a sensor . You may want to stick with a standard lens for whatever sensor you have in order to get the most natural perspective in your image .
I always felt that rules are made to be broken. Rule of thirds etc. are guides that help us learn and developed our own style. Thank goodness we all don't like the same think or life would suck if you ask me.
Had a 1959 100-6. vapor lock was a problem on hot road trips as well a melting cheap snickers on the floor by the peddles.
I have had some very good shots with D750 and a 200-500 Nikon.
You could pack lighter and take a 14-24 f2.8. A very sharp lens.
Check out the iPhone app that controls the camera through the in camera wifi.
I have my D750 set so I can control the ISO with the front wheel. It's very good way to do it.
You need to figure out what makes you enjoy photography and take it from there .
I love mine. Great low light ability and shadow detail without the large files of the D800 or D810. Not a small camera but have not found that a problem.
It's totally subjective, you like what you like and no two people are going to like the same photo for the same reasons. What makes it good will be different for all of us. Thank goodness we don't all like the same thing.