First of all, ideas
Most oil paintings convey the author's emotional infection with the things depicted. Only by understanding this emotional infection and the author's purpose can we better understand the work.
Second, composition
A successful oil painting must have a good composition.
Third, performance.
If the shape is correct, it is still abstract, and elegant colors are still bright.
Fourth, the subjective familiarity with the work means that your feelings are infected. In short, do you like it?
Most of the famous works have a wide influence and are the continuation of predecessors, so it is also important to analyze their background.