Lately I've noticed that the photos I've snapped with my iPhone 4 have looked less than sharp. Fuzzy, even. I tried a couple different photo apps, as well as some video recording; same result.
I checked the lens to make sure it didn't have any dust or other flotsam on it, and it seemed fine. But on closer inspection, with the light hitting it at just the right angle, I discovered the problem: a fingerprint.
Somewhere along the way (probably while pulling the phone out of my pocket), I'd managed to muck up the lens with my finger.
OK, so what's the best way to clean an iPhone camera lens? If it's an iPhone 4, the process is easier than you might think. That's because on that model, the lens cover sits flush with the back of the case. Using a microfiber cloth or even a soft shirt, you can clean the cover with just a couple quick breaths (to provide a bit of moisture) and a light wipe.
Older iPhones (namely the 2G, 3G, and 3GS) have recessed lenses that are harder to clean. (They're also harder to accidentally smudge with your finger, which is the plus side.) For those models, I recommend a cotton swab and, again, a couple quick breaths for moisture. (You could use a bit of lens cleaner, but you don't want to risk any of that seeping into the iPhone.)
Once I'd given my lens a quick cleaning, photo and video quality improved dramatically. I didn't realize just how bad both had gotten. The moral of the story: every few days, or even just before you use the camera, give the lens a wipe.
If you have any lens-cleaning tips of your own to share, let's hear 'em in the comments!