I could not find a perfectly flat spot. I also wedged it so there was pressure for the pad and glue to set over night.
The sticky pad included is ok but i wouldnt trust it. After riding for 3 weeks i had my camera out one day and noticed it was coming apart. Not were i glued it to the helmet , but were the small foam disk(sticky pad) attaches to the camera mount itself...so more super glue. This probably due to me adjusting the angle of the camera a few times. Now i feel it is secured for life.
My helmet doesn't have a flat spot or a surface area to match the adhesive size/shape yet it sticks there just the same. (clean the helmet first with some alcohol to make sure there's no dirt or grease)