This is a very important tip for those who choose to shoot out of Auto Mode. In Auto Mode the camera thinks it's smarter than you, prove it wrong! This tip will contribute to sharper photos and may be one of the best basic tips you can ever remember. Lens aperture has a sweet spot that is not too open and not too closed. It generally gives the best results all other considerations being equal.
I love this site and I will post more tips in the near future.
http://www.adorama.com/Catalog.tpl?op=academy_new&article=091507

Best,
Warren