Start with clean hands, but try to avoid using alcohol wipes, says CR's chief medical adviser Marvin M. Lipman, M.D. "That can diffuse the blood drop, and possibly make the reading artificially low." Instead, simply use soap and warm water, and dry thoroughly; the warm temperature helps the finger capillaries to dilate.
Also, don’t milk your fingertip for blood because that can dilute the blood drop with tissue fluid and may cause a low reading. To get enough blood for the strip, brace the tip of your finger against a stationary surface, then prick it with the lancet. For related information, check our blood glucose meter buying guide.