Just the other week I discovered that you can get the hole for the brad in exactly the same place on each corner by using a square of plastic canvas used for yarn embroidery. You lay the corner of the plastic canvas on top of the corner of your card/paper then you can use the holes as measures for where you want your brad. You have to make sure that you push your brad through the same part of the hole in the canvas for each corner. I've seen people use plastic canvas to make mock stitching lines but not to ensure their brad holes are spot on. It used to drive me mad when I got one brad lower in one corner than the other. Maybe it's just me that does that but possibly I'm not the only one.
-Ann Cutts, TPE design team
Another alternative if you don't have plastic canvas on hand is to use a piece of scrap cardstock. Determine where you want your brad on the scrap. Punch a hole in the spot. Now, lay your scrap card on top of the card you are setting your brads into. Punch a hole through the existing hole and into your card in the upper left corner. Flip the template from left to right and lay it on the upper right corner of your card and punch. Now, flip it from top to bottom and punch the bottom right corner. Flip one more time from left to right and punch your final corner. Set your brads in the four corners. They will all be lined up evenly.
-Robin Willis, TPE design team