One thing for camera shake - I find that as a general rule of thumb you usually don't need to rest the camera on anything if the shutter speed is equal to or higher than the focal length of the lens i.e 50mm lens, don't go lower than 1/50th of a second before getting support. And if you're using a zoom lens (which is the standard lens for most of the SLRs sold today), use the larger figure as your base calculation i.e 35-80mm, don't go lower than 1/80th second without support.