Gather all of the pictures or artwork that you want to hang on your walls. It's a good idea to choose photos of varying sizes and shapes to cluster together, or you can hang similarly sized artwork equal distances apart for a clean, modern look.
Lay brown paper bags or some other type of shaded paper on your work surface, place your picture on top of it and trace the outline. In this way, you can make a stencil to help place your pictures before actually nailing them to the wall.
Use removable tape or fun tack (gooey substance that teachers use to hang posters) to secure your stencils to the wall evenly. You can easily move and reposition them until you find an arrangement that you like. Mark the position of the stencil so that you can align your pictures with it.
Hammer nails into the wall where you want your pictures to hang. Be careful to follow your markings correctly and hammer into studs if they're available. If there isn't a stud, you might need to purchase wall anchors.
Hang your pictures in their assigned positions. The arrangement should come out exactly as your stencil arrangement suggested--evenly spaced.