Just like Roary, dick pics. Always shoot from an upper angle, make sure you have good lighting, put your nicest watch on the arm holding your dick. Whatever you do, don't shoot from a low angle, they don't want to see your balls, if you have good abs, take off your shirt and shoot from a even higher angle, so she gets a taste but not a full drink of your abs, just enough for her to want more.
Follow this guide and you will make millions using both heads in no time!