Balance and Imbalance
Many beginning photographers place their subject at or near the center of the frame, either consciously or unconsciously. I guess the compositional intent is to avoid an unbalanced shot. But it doesn't really work that way.
It's time to take a look about this whole topic of balance. As I alluded to above, it's easy to accept the reasoning that a balanced frame doesn't crowd into either side of the frame and an unbalanced one focuses attention to just one side of the frame while wasting the other. But that ends up boiling down to placing your subject in the dead center in the middle and zooming to fill the frame. And that can't be right. Right there on the photographer's top ten things not to do is to bullseye the subject.
When I consult a dictionary, I read that "balance" is "the state of having your weight spread equally," but it also says that can be a "state in which different things occur in equal or proper amounts or have an equal or proper amount of importance." While this first option would support placing your subject in the middle, the alternate definition opens things up a great deal, and almost always results in more compelling images.
So what does it mean for things in a balanced image to occur in "proper amounts" or have "proper importance?" Clearly, the key point involved here is the idea of "proper," but what does that mean? That same dictionary defines "proper" as being "correct according to social or moral rules." So a well composed, balanced shot is one that follows the rules for creating well composed, balanced shots?" Kind of circular logic, isn't it? So much for the dictionary. Maybe we need to figure out our own rules.
Let's try thinking of balance versus imbalance as sort of a "Zen" or "feng shui" thing. It's not so much in the domain of a thinking as it is a sense of feel. Does the balance "feel" right? If you place your main subject somewhat to the left but counterbalance it with complementary or contrasting elements on the right, the overall image can still feel balanced when you look at it. Mission accomplished, even if such a victory can seem a tad nebulous and hard to apply to photographers working at figuring out what it all means.
Perhaps it can be worth considering this instead as being like a basic children's seesaw. We're talking here about a sense of balance, after all. Imaging you are sitting by yourself in the seat at one end of the beam, with the empty seat on the opposite side of the fulcrum high in the sky in front of you. You aren't likely to have much fun down there on the ground with the seesaw siding with gravity rather than caring about your fun. One solution would be to sit directly on the fulcrum of the seesaw rather than in either of the two end seats. While this would restore balance though, it won't likely improve your enjoyment factor for very long, given that the seesaw still won't go up and down. There's no movement.
The compositional faux pas equivalent of sitting on the fulcrum middle of the seesaw would be the beginners mistake of always placing their subject dead center in the frame. While this technique does provide for balance, it generally won't create images that are much fun to look at. An image that avoids this dilemma but still feels "properly" balanced is one that has equal weight on both sides of the frame but still has a sense of movement.
There's no reason you need to have exactly equal items on each side of the frame either. A seesaw works just as well when occupied by twin brothers as when one of those brother is replaced by someone entirely different but still of equal weight. Or a guy holding a heavy object. Or any other combination of objects that still provide for balance. I often find aspiring photographers trying too hard to create both balance and movement by offsetting one subject with another identical item, or one that is just too close in appearance to the first. This can easily confuse a viewer, causing the eye to ping pong between the two apparently equal potential focal points. It wouldn't be at all clear which of the two was the intended subject. And attempting to say that both are co-equal subjects doesn't help much since it fails to address the ping pong problem of the viewer's eye travel. What you want is a clear main subject, together with some number of complementary counterpoints to provide weight to the balance of the frame.
When avoiding the center of the frame though, don't fall victim to crowding the edges either. There isn't much that grabs a viewer's attention more than a high contrast annoyance right smack on the edge of the frame that doesn't seem to belong there. Think of the disconnected tree branch intruding into the frame's otherwise clear blue sky with no tree anywhere to be seen. Think of the half visible tennis shoe on the sidewalk down in the corner, cut off from the leg of the person standing just outside the frame who was wearing it. You know what I mean. These sort of distractions along the edge of the frame may as well be made from depleted uranium or some such substance, they have so much visual weight in the frame. Inadvertently, vertically oriented (portrait mode) shots can easily end up with edge problems or center problems given how little space there is to work with from left to right. So much so that I try to consciously check for such cases.
As mentioned already, achieving this sort of mystical balance together with movement often comes down to feel. You know it when you see it but it can be hard to reliably preplan and intentionally achieve. Getting better at this will mostly come from experience, but it can be helpful to work out the words to describe why a good image feels balanced. Cognizing the unspoken rule can help you find balanced images more quickly next time. But any "rules" you work out this way will be your rules, not ones that just came from books. You can definitely create good images by using rules from a book, but to get really good at it you have to jump off into making up your own rules.
This sort of balance can be a tricky thing to master. But it can also be a lot of fun.