Drew and I have used the lipstick trick with hanging Sheetrock. It helps mark out where to cut existing lights, boxes etc. This time I used it to arrange my gallery wall. First you smear some old lipstick onto the piece of art you want to hang, where the nail will hold the piece. Then line up the piece on the wall, when it is where you want it press the piece against the wall.
It will leave you a guide right where your nail need to go. Sorry these pics are low quality, just had my phone on hand.
Look at that aim. And yes the only nails I could find were from Drew's roofing nailer.
I use this trick on everything. Canvas art...
These little jagged brackets.... And if you mess up, you just wipe it off and reapply.