Always try to keep the ISO as low as possible. Sunny days are usually bright enough for you to use the lowest setting (which is 100 with Canons, I'm not sure about Nikons). Overcast days will usually mean having to up the ISO to about 200/400, and 800 if it's getting really dark. 1600 is just a no go. :tuttut:
Of course, the ISO setting should always be judged, rather than just thinking "it's cloudy, so ISO 200 it is". If you're wanting to use a high shutter speed, or very narrow aperture, you may need to up the ISO to get the right exposure, even on a bright day, and vice versa.



I suffer from paranoid amnesia. I can't remember who I don't trust.






