Hammer nail through a wooden ruler. Hang picture on that nail. Line it on the wall where you want it. Remove picture, push in nail to make an indent. Remove ruler, hammer another nail into the wall Hang your perfect picture up.
How to get hummingbirds to nest! I love the mosaic look of the moss that humming birds sculpt onto their nests. Humming birds are very allusive but some people have actually trained them to trust the human hand.