Then there is the subject of blind spots.
I've been shaving for more than 50 years now. During that time, not much changed. Sure, I've always used the latest razors -- usually from Gillette. The shaving cream, always from an aerosol can, has changed a bit over the years. Stainless steel blades came along, and they lasted longer than carbon steel; double-edged blades morphed into single-sided razors with ever-increasing number of blades, and the shaves got a little closer, but, for 50 years the quality of my shave didn't change much. For most of the last 25 years, I used one shaving cream, Edge. A couple of years ago, I had a cancelled flight and had to spend the night without my checked luggage. The hotel desk clerk supplied shaving cream, which I liked a little better than Edge.
That one little change ended 25 years of shaving stasis. I started randomly buying different kinds of aerosol shaving creams; some were good and some weren’t so good, but there wasn't all that much difference between them. Finally, I happened upon a shaving cream from Italy that came in a old-fashioned metal tube (Proraso, if you’re in the market). It felt different, it smelled different, and it worked a heck of a lot better than all the aerosols. I went through a couple of tubes before I started to wonder if I was using it right. I bought a book on shaving (Imagine that! What's next? A book on brushing your teeth?). It turns out that I was indeed using it wrong: I was supposed to froth it up into a lather with a brush before putting it on my face. I bought a badger brush and a little stainless steel rack so that I could hang it upside down and let it dry out between uses. It took some practice to get the ratio of water to shaving cream right, but I persevered until I could consistently achieve a rich, thick lather. The result: a closer shave than I had ever imagined; a difference far greater than 50 years worth of progress in razors. I've since found another shaving cream that performs almost as well (Musgo Real, made in Portugal), and I suspect there are many others out there.
You're driving down the freeway in your car, and you’re thinking about changing lanes. You glance at your mirrors and you don't see anything. But you know there's a blind spot there, so you look over your shoulder before you turn the wheel. We’re talking about blind spots here, but they're more insidious than the ones you deal with in your car. You know where they are. My ignorance about shaving was a blind spot I didn't know was there. Call it a double-blind spot. I had been going along for most of my life thinking I knew everything I needed to know about shaving. It never crossed my mind that there might be a serious gap in my knowledge. Not only did I not know how to make my shaving experience better, I had no idea that it could be made better. For all that time, there was an opportunity for improvement that was completely unknown to me.
Donald Rumsfeld took a lot of heat for his didactic ruminations on "unknown unknowns", but the concept accurately generalizes what we’re talking about here.
If unknown opportunities for improvement can persist in something as simple as shaving, they are far more likely in a complex and varied activity like photography. It is almost certain that there are things we can do to make our photography better, but we don't know where to look for them.
One conceivable approach to discovering double-blind spots is to systematically take apart the way you make pictures, looking for alternate ways of performing each of the steps involved in photography. I don't think this is a highly productive path. If you've been making photographs for some time, it's become an organic activity, and thus one that is difficult to break down into its complement parts.
If self-analysis doesn’t seem like a winning strategy, what does? For my money, the best way is to make photographs with others, and pay attention to what they do. You can do this in a workshop, a course, or informally with your friends. If you are an experienced photographer you may be tempted to ignore workshops. Don’t; even if you don’t learn anything new from the instructor, you can learn a lot from your fellow students. The key is to be on the lookout for things that people do that are different from the way you do them.
If you are an experienced photographer at a workshop, you will undoubtedly be called upon to do some informal teaching. This, too, is a learning opportunity. If you’re trying to explain how to do something, one of your students is likely to ask you why you do something the way you do it, and in coming up with an explanation, you may realize that there are other, perhaps better, ways to go about it.
If you are comfortable with a cerebral approach to photography, you can figure out where your blind spots are by reading a lot about photography. Don’t just read about things that are new to you; read about things you think you already know backwards and forwards.