If there's one thing I have complaints about concerning the iPhone, it's the camera. All in all, I have more complaints than that but let's focus this post on making the most out of a mediocre situation. At a rather meager 2 megapixels and lacking a flash of any kind, it can be tricky to get photos that aren't blurry, let alone acceptable to share with anyone. The addition of more megapixels would most likely create even more problems due to the technical limitations of the iPhone's lens, but if certain requirements are met, the little do-it-all device can be useful in a pinch as is. Most of these techniques apply to photography in general and are extremely useful for any kind of camera phone.
It should go without saying that lighting is one of the most important aspect of taking a great photo regardless of what camera you're using. It becomes even more crucial when using a lower quality lens such as those found on most camera phones. The iPhone's lens is very sensitive to different lighting situations which is more of a good thing than bad.
Let's examine the photos of the flowers to the right. In the first shot the camera underexposed the subject due to the bright window in the background. In the second shot, I moved so that the wall would become the background, resulting in 
a much better exposure. Even light, such as outdoors on an overcast day, results in great looking photos.
In addition to good lighting, another step you can take is get close (but not too close) to your subject. In my experience, the iPhone's camera lens focuses best at about 2-10 feet. Any closer, and the subject is blurry. Any further away and the subject can get lost in the composition.
Another step to getting the most out of your iPhone's lens is to keep a very steady hand while shooting. Since a tripod is not an option with the iPhone, try bracing the device against a wall, tree, lamp-post, or any other steady object you may find handy. This is very useful in low-light situations where camera shake is much more obvious.
Lastly, don't be afraid to get creative with your photography. Get low to ground or stand in a chair. Anything you can do to make the shot more interesting could turn a good photo into a great photo. It won't do much good if the other ideal conditions are met when taking a shot, if the composition is poor. Stand in a location and frame the shot to draw maximum attention to the subject.
Good use of ambient light, getting up close and personal, holding the iPhone steady, and great composition of your subject can all lead to better photography in general, and can make a huge difference when taking pictures with your iPhone.
