I think the iphone 5 has a pretty decent camera in it. I know Yancy is impressed and he's a real pro at taking pictures.
I have a iPhone 4 and my wife Stacy has the 4s and the quality of the 4s is much better than my 4
I take and post pictures using my iPhone 4 from time to time, mostly when I don't have the Canon Rebel with me because I think a good lousy picture is better than no picture.
A picture says a thousand words and no picture in your write-up, website, or FB page says nothing.
I agree framing-up a shot is also important. When I take pictures for SEMA I don't have time to do a lot of cropping, just resizing and uploading, so I try really hard to do a great job of framing up my shots before I click the shutter button and it helps a lot.
Like mentioned above by Bill and others, study the manual that came with your camera and the practice practice practice. Pay attention to the settings that are working for you, your subjects and your work environment.
Learning how to add some text to your pictures can also be a huge help to "guide" your viewer and make sure they see what you want them to see. I did this recently in these two threads...
Here's why you need to polish paint...
1955 Chevy & 1947 Buick Slantback - Show Car Makeover! - Pictures & Videos
Here's Mike's car and in this picture it can be kind of hard to see where I buffed on the top of the front driver's side fender.
It's still hard to see the before and after difference, but for reference, I've taken the same picture above and placed an arrow pointing to the tape-line where I buffed on the front edge of the fender and left the back side of the fender along.
Now look... see what I mean by embedded dirt on and to some level, "in" the paint.
Here's another recent write-up I shared on the topic of capturing defects...
How to photograph and capture swirls in the sun
