First you have to realize that good images and good cinematography are two different things. It is still a concept I am struggling with right now. Initially everyone just tries to make the prettiest images they can make, especially when they get very obsessed with making a great reel (I am no exception) but something that is not talked about enough is judging cinematography by how well the images help to craft the story of the narrative. This is something that is not as easy to put down into words, but if you can get really good at it, you will be a good cinematographer. I would recommend starting by asking what the narrative motivation is for every decision you make, whether it be camera placement, lens choice, lighting setup, movement, etc. Hope this helped, and happy shooting!