I don’t use the camera in my Nexus One as my primary phone, I have a Panasonic Lumix DMC-FZ7 that I use to take quality photos, and a smaller Panasonic point-and-shoot when I don’t want to carry the larger FZ7. However, I still take a lot of photos with my Nexus One mainly because the phone is usually with me when I see something I want to shoot. Unfortunately, getting a good picture with the Nexus One seems to be a based mostly on luck.
Zack Stern of PC World has an article titled, Take Better Photos With Your Android Phone with suggestions that should work regardless of which mobile phone you use. For example, he suggests using flash for daylight pictures to compensate for under exposure on sunny days. Not all camera phones have the settings that Zack has on his DROID, for example, I don’t have the ability to change the ISO setting. Perhaps the best tip for taking better pictures with your phone is to learn all of the camera settings on your phone so that you can take full advantage of your camera’s ability.