Hi, first off I spent many happy hours around Scotland, all areas, here's a tip, take say maybe 3 or 4 pics each day, even if it's from your front door..At one time I kept a small book with details of each photo (just 4 one month) then I go back and use different settings from the same viewpoint..As for a Grey Card" I use the ground, depending on how your camera is set up, you can use shadows, bright light & then use the average..