The first step in developing and strengthing our ability to understand and interpret art is to learn how to be curious. At first, this probably seems simple or redundant; any child can be curious. Nevertheless, real curiosity requires careful attention. In fact, curiosity is more like a muscle than it is a skill. As we use it, it grows stronger and more capable. Once strong, our curiosity will open new avenues of inquiry, allow us to be more efficient as we arrive at and ask the right questions quickly, and bridge the gap between known and unknown material. Nevertheless, like a muscle, it becomes weak and atrophied as we ignore or misuse it.
In a very real way, developing our capacity to be curious is one of the main reasons we study art history at all. Few that engage in it will use the details of style and history in a significant way during their daily lives; however, everyone that develops a strong capacity for curiosity will use it daily in every aspect of their life. It is what fuels lifelong learning and permits continual personal growth.
In its most basic form, curiosity is merely the ability to ask questions. However, not all questions are equally useful or relevant. Strengthening our curiosity means learning how to identify and form the best questions. These are the questions that give us the best possible information in response. Essentially, we pose questions that the artwork helps us answer. If our questions are vague or poorly stated, the artwork responds in kind. If we offer questions that are carefully crafted, specific, and earnest, the artwork will reveal its secrets.
There are two important components to effectively flexing our curiosity. First, we must be sincere. Second, we must be responsible. Let's look at these two components in more detail.
Sincere
To be sincere is to be genuine and honest in our questions. It means to ask questions that reflect our real interests. These are questions that we honestly want to have answered. Too often we can find ourselves forming questions merely to form questions rather than to engage in learning. For example, imagine that we are exploring this work of art by Leonardo da Vinci, entitled, "Portrait of a Musician."

We might quickly formulate questions that are neither sincere nor responsible, such as:
"Why does he have a red hat?"
"How does this work reflect the style of the time?"
"What is the piece of paper in his hand?"
"Why is the background black?
Instead, we must first identify the features we are truly interested in to ask sincere questions. Sometimes we can understand this by engaging our own less-valuable questions a little further (you can check out the Tier 1 list of artistic elements for help with this). Let's try that with the first question above. We might ask ourselves why the red hat interests us and what features have encouraged us to think about it. Perhaps we find the shape of the hat odd or uncharacteristic of this period, according to our experience. Or perhaps it is the color that strikes us, since much of the rest of the work uses browns and black. Once we have identified the feature that truly interests us (let's say it's the color), we can begin revising our question. Instead of "why does he have a red hat?" perhaps the question could be "does the use of red on the hat indicate something specific about the subject" or "was the choice for a red hat made by the artist or was the subject actually wearing a red hat at the time of this painting?" Neither of those questions are yet sufficient, but we have moved toward a more specific and sincere question, one that reflects what we are actually interested in.
Another aspect of sincere curiosity is related to the form our questions take. If, for instance, we are asking questions that yield a short and definitive statement, we are likely insincere in our wondering. The third question above about our musician, for example, is this sort of question. The answer is plausibly and succinctly, "a piece of music," and our inquiry ends as soon as it begins. Instead, we might revise our question to reflect our real curiosity by focusing on the features that caused us to form our original question. Perhaps the composition of the painting is our real concern; it appears that the piece of paper in his hand is directed to the viewer specifically rather than a representation of the subject (that the viewer is intended to read what is written on the paper rather than understand it as something the subject is using). If that were the case, we might revise our question to be, "In what way is the viewer to interpret the piece of paper?"
Responsible
Sincerity alone is not enough to formulate the kind of questions that lead to a better understanding of a work; the question must also be responsible. To be responsibly curious is to ask questions that are appropriate for the setting and that are answerable. Let's deal with these components one at a time.
Appropriate
Asking questions, and being curious, has consequences. The questions you ask yourself or others may inspire further curiosity, leading you down an unknown path of discovery and learning. This is an inspiring and wonderful lifelong pursuit that yields growth and illumination. However, sometimes those paths contain unexpected turns or challenging realities that we or our companions may not yet be ready to explore due to lack of maturity, life experience, or other limitations. Part of being responsibly curious is to be aware of and accountable for the consequences that come as a result of our curiosity.
Answerable
There is little benefit to asking questions for which the answers are entirely hypothetical and based on little evidence outside of a thought experiment. To be responsibly curious means to ask questions for which we could find answers if we had more time and resources. For example, the question above, about the black background, will likely be difficult to answer no matter our time and resources. Perhaps Leonardo is the only person who could offer any light on the subject and sadly, he is unavailable. Instead, we can formulate this question to suggest an answer which is within reach, such as, "why didn't Leonardo paint a landscape in the background as he did with the Mona Lisa?" or better, "what role does the background have in Renaissance portraiture?"
Learning to be sincerely and responsibly curious is deceptively challenging. You must learn to ask the best, specific, honest, appropriate, and answerable questions. Though difficult, mastering this skill is the key to understanding and deciphering unknown content. Beyond the world of art, it is a fundamental principle of lifelong learning.