Grouping Mirrors: How-To
Paint your selections an acrylic hue that complements the color of your wall. Start by laying the frames out on the floor and fiddling with their positioning until the arrangement is to your liking.
So you can easily transfer this grouping to the wall, trace frames onto paper and cut out.
Affix the paper templates to your wall in the desired positions with low-tack tape, and use to mark where to hang.