It happens to the best of us. Photography fails are forgivable as long as you do it like a pro and avoid these seemingly obvious noob mistakes.
Using Flash Outside of Its Useful Distance
Flash can only really help brighten subject matter that is close by, this is especially true for built in flash. If you are doing some advanced flash work then you get away with using it, but you wouldn't need this pointer if you are doing that...
Confusion with Dial Modes
Obviously you don't NEED to know the name of each setting or even what it means, all you really need to know is what those settings do to your camera. Mastering the MASP modes is key, where as the other standard modes aren't nearly as important.
M is for manual: you will have full control over shutter speed, aperture, and ISO.
A is aperture priority: you will have control over aperture and the camera will select shutter speed.
S is for shutter speed priority: you have control over shutter speed and the camera will select aperture.
P is for programmed mode: in this mode, shutter speed and aperture are paired to create a well lit photo, but you can change either setting and the camera will make sure you are still getting your shots perfectly exposed.
Getting ISO Wrong
People commonly forget about ISO, what is does and how to change it to suit the environment you are in. ISO essentially determines how sensitive your sensor is. The higher the ISO, the more sensitive it is to light and the brighter your image will be in less light. However, with higher ISO (especially extremely high settings) you will start to notice a loss in color and sharpness, and more grain.
Putting Your Lens Hood Backwards
Lens hoods are great for tool for limiting light going through the lens, it is usually used to prevent glare or lens flare. However, people often put them on the wrong way, and when they are backwards they do nothing! I understand some people put it on backwards as a way to store it if you aren't using it at the moment. That's fine, I do that too. Just as long as you know it's not actually doing anything while it's backwards.
Shooting with Your Lens Cap On
I have to admit, I do this quite a bit. I will take one or two shots and realize I have it on and then take it off. However, many noobies may try to start adjusting things as if their images are just under exposed. Always make sure to check it your lens cap is on, and if you take it off don't lose it!
Forgetting About White Balance
White balance is the process of removing unrealistic color casts, so that objects which appear white in person are rendered white in your photo. You should change your white balance depending on the type of light you are shooting in. A properly white balanced image will have whites that are white, not slightly blue or slightly orange....
Of course if you are shooting in RAW and you are editing in Photoshop or Lightroom then you can correct any white balance issues once you get them on the computer. However, I was always taught to get it as close as possible in camera and I think that's a good habit to have!
Choosing Between Manual-Focus and Auto-Focus
Often times I will see someone switch to manual focus to get a shot focused just how they want it, but they forget to switch to auto-focus when they really need it! There are some instances when you need both, and time isn't always on your side when capturing photos, so make sure to set focus type before you even want to take a photo!
Being Poorly Prepared to Shoot
There is nothing worse than getting ready for a big day of shooting only to realize your camera batteries are dead. You have to make sure everything is in order before you go off shooting!
This means remembering to get your equipment ready for the job AND bringing the necessary tools for the job at hand.
Improperly Loading Film
I know many students start off shooting film photography in school, but in this day and age most of us are not trained in shooting film. I know I had to learn all about shooting film after already learning digital!
If you want to shoot some rolls of film, make sure you know how to properly set up a roll of film so you can actually taking pictures.
Forgetting to Rewind Film
I did this once and I hated myself for it! The camera was only open for a fraction of a second but pretty much all the images on the roll were a complete loss. Make sure that you wind the film back into the cartridge before taking it out. That film is light sensitive and all the pictures will be ruined if you open the camera without winding it!