If you’re setting up your own props, of course pay special attention to their composition, and like another reply, ensure you’re close enough and that your subject fills the frame (of course, sometimes breaking this rule can be effective too). Pay special attention to the background and areas that are out of focus. Ensure there are no distracting elements or things that will haunt you later when reviewing your photos If you’re outdoors, lighting is important. Actually, wherever you are and whatever you are shooting, lighting is very important. A cloudy day is, believe it or not, probably the best light because it will be diffisued and not very harsh, but you will lack shadows if thats what you’re going for. If the light is too harsh, consider using some sort of diffusing material (any transluscent materual) which you can hang between the sun and your subject. Consider also using reflectors (homemade stuff works just as good as the expensive reflectors you can buy from photo stores), to reflect light back into areas of your image that are too dark.
One of my most liked situations for shooting with natural light is finding a nice window that is not in the sun’s direct path, placing my subject next to it, and having a reflector on the opposite side. Makes great results.