O.k. I get this question every single time a customer picks up a Portrait so here goes.
Step one: Select a wall in which the Portrait is going to hang. Unless it is a Gas Fireplace avoid placing it there. The ultimate location is in the Living Room above a couch. This is great for horizontal prints and colloages.
Step two: One you ( usually the guy) holds the portrait apporximately where it is to hang while the other checks form several feet away that the portrait is level.
Step three: Using a pencil the person doing the checking marks a little undentation on the wall on the top left, right and centre of the frame. Exacting on top.
Step four: Measure the width of the frame. A 3 inch frame would require that you screw in 3 1/4 inches below the marks.
Step five: depending on the weight use 2 to four flat head screws. If possible try to a)find the brace, us 3 to 4 inch screws, screwed in 3 quarters of the ways in and c) you may need dry wall plugs
Step six: Remember, cielings are alway off and so are floors so measuring from either will guarantee a slanted photo. Once you have the portrait on the wall put a smal amount of pressure on the top of the frame to create groves the the portrait will sit in.