So I didn't have a grid system, I honestly wanted to just stick these up and forget my popcorn ceiling ever existed. I used liquid nails with a caulking gun to apply a layer of glue to the back, then as you can see from the pics, I hit the back of a screwdriver with a hammer to pop a little hole in each corner to make a guide so screwing in the screws would be easier. I put one screw in each corner and just waited for the liquid nails to do its magic. It turned out pretty well, my ceiling is really crooked. It is definitely an improvement from the popcorn ceiling.