I don't think you have to be any sort of professional photographer these days to take good photos...I use a digital canon powershot A710 IS. It's a 7 mega-pixal. I mostly shoot on the auto setting, but you can use the manual settings if you are into all that type of stuff. I'm mostly a point and shoot type of photographer...
All that being said,, I normally get great photos with excellent details on my photos that I use on my auctions..My suggestion to you would be to get your self a good quality digital camera. By that I mean that it dosen't have to be an expensive one,,just a good quality camera, and of course, the more mega pixals the better.
I most always use a shadow box for everything that I can. You can pick them up pretty cheaply on ebay. This way the lighting will always be correct when you shoot the item and will also make it look professional..Too, when shooting apparel, try to use a background color that makes the colors of your apparel stand out, or at the very least use a contrasting color for your background..
Too, shoot several photos of the item and then choose the best photo for your listing. Sometimes I might re-shoot the item several times until I get a quality photo, but good photos will help increase sales...