A tried and true method of hanging wall art/photos. Cut scrap paper to the size of the frame and mark the nail location on the paper. Using painter's tape, move the paper templates around the wall until satisfied. Then hammer the nail through the marks. Remove the paper template and hang!
Pretty much the best website ever: knockoff DIYs of retail decor. (anthropologie, ballard design, crate & barrel, land of nod, pier 1, pottery barn, restoration hardware, urban outfitters, west elm, williams-sonoma and others). Truly some of the neatest ideas ever!! - Sounds like it's worth a look.