Rules are things such as:
- Sunny 16 (f/16 1/125sec for photographing the sun)
- Catchlights in human eyes
- Using short lighting
- Color cast removal
- Never centering an image
- Specific uses of light
- Angle usage
These are just a few examples of things you may have heard of/been taught. And many people probably follow them without a second thought.
The rules aren't so much rules, as they are a foundation though. They're a starting point for learning, on which one can build. Everyone needs to learn and use the rules to start--it's just a good base to get yourself started with. It's a way to see how a photo will be effected by certain elements. And by forcing yourself to use the rules at first, you will learn to be a careful photographer who plans a shot. Planning allows for a finer execution 90% of the time, and can really make the difference in many cases.
Of course, once you have the solid foundation, you have to start building the creativity on top of it.
Photography is nothing but a big experiment. By learning the rules, and using them, you've created a control for yourself; think back to science labs on this one. Now that you have a control, you can start breaking the rules and experimenting to see what works, and what you probably never want to do again. And since you have the control, you'll be able to identify just what it is that's causing the effect you're getting.
For example, the Sunny 16 rule states that when photographing the sun (or moon, since it's a reflection of the sun) you should shoot with an aperture of f/16, and a shutter speed of 1/125 sec. This does indeed produce a crisp sun or moon with no halo. And in some cases, it's a beautiful capture. But maybe you want a gentle gradation and for the sun to really blend into the sky or sunset. You can leave the aperture alone, and try slowing the shutter speed down, or you can leave the shutter speed and open your aperture up more; at least to start. Then maybe you'll stop down or up. The choices are endless, but because you understand what the Sunny 16 does, you'll understand what's going on in your experiments all the more. And for someone who is just starting out in photography and really getting to know their camera, this can be a crucial learning point to really understand what each function does. After all, hands on is usually the best teaching tool!
The other thing we must always bear in mind though, is that the rules came about because they work, and almost always create beautiful imagery so long as the creativity is there. So when people look at your photography, they may be a bit adverse to your experimentation. Don't sweat it. We all have a personal opinion, and everyone has certain things that they just don't like. You're going to meet personal opinions all over the place, and most of the time you just have to let them go.
My suggestion: Don't take the advice unless you hear it from three or more people, or over 50% of the comments echo the same feeling (depending on how many you get). If multiple people feel that you didn't do too well in one aspect, then chances are you could do better. But just one opinion doesn't mean too much a lot of the time. After all, it's only one person.
Why do I say this?
Let me give you an example.
A big thing right now in the world of photography is the use of angles to create interesting views. Photographers all over are tilting their cameras and their photos to come up with more interesting crops. The rules state that you shouldn't do this. Most people out there really enjoy it when this rule is broken though, and so the angles have become quite the fad. Me personally? I usually hate angles. It's not because of the rule, but it's because unless they're done really well, I feel like the subject is falling out of the frame most time.
So if I were to comment on a photo taken that uses the angle idea, I would probably mention that I don't care for the angle much. However, I wouldn't expect that advice to necessarily be taken because the majority of people who left comments will probably love the use of the angle.
Basically, this means when it comes to these "rules", you do need to learn them before you break them. They will be a good foundation on which you can build. Don't get hung-up on them though, because it's the rebellious that get noticed. Use them to find what works for you, get rid of what doesn't, and improve yourself. And don't let anyone's opinion get in your way of this journey because remember, everyone has one and most of them stink.