A tripod, if you don't already have one, would be a great idea. But if you can't get one just yet, check if your camera has a delay setting. Set it at the shortest time that's not zero. Default setting's zero; when you take the picture, it's possible that the action of simply pressing the button moves the camera a bit. Setting the delay slightly longer prevents that.
I personally am a cheapsake and have simply used my desklamp (incandescent) as a light source, with maybe a bit of extra light from a super-bright flashlight. Sunlight's the best, though, especially when you are trying to capture the true colors of stuff. I would not use florescent or halogen lights. Both emit mostly one type of light (yellow for halogen, blue for florescent) and this adversely affects your pictures http://www.mtholyoke.edu/~mpeterso/classes/phys301/projects2001/awgachor/awgachor.htm
. Brightness also matters--the brighter it is, the less time your camera will have its shutter open, the less blur you will have.
Oh, and make sure the little flower icon is not on for the full-length pieces. That's the 'macro' icon--use the macro setting whenever you are within 2-4 feet from your subject (the clothing piece). You may have a supermacro setting--that's for 2-4 inches
, if you ever need to take a detail pictures. http://drscavanaugh.org/digitalcamera/macro.htm
Oh, and watch the zoom. Typically, they start by using the actual zoom lenses but then switch to "digital zoom", which looses focus. Never use to the digital zoom. The boundary between the two is marked by a small vertical line.
I hope this all makes sense.....