There are different genres in painted art as there is in music. For starry night van gogh there are basically several ones that you can consider. From Classic to Renaissance and then fast forwarding straight to the era of the expressionists and impressionists there is a vast array of options for one to consider.
Having a keen eye for art does not always mean that you need to know every single type of brush stroke or be able to analyze the composition of van gogh irises immediately. For collectors who are making an investment, it is indeed a necessary tool to know as much as you can about almond blossom because of the fact that money is involved. But in cases where in the value of appreciation is considered more than the monetary value, a keen eye would basically represent knowing how to love the painting for its content.
Learning to appreciate a painting is seeing where the beauty of the painting lies. It may be aesthetically pleasing to the eyes such as classical techniques similar to that of the times of the Greeks and the Romans or the dream like feel of the works of Rembrandt and Da Vinci from the Renaissance period. But there are also cases where in there is much to decipher and analyze when looking at a painting for the first time such as the works of Van Gogh Paintings which are termed abstract.