I use hotglue. The easiest way to make sure theyre in the right place and invisible and look real, is to get a headband that matches your hair color or is small enough to hide in your hair. First, put on the headband and hold up the ears on the headband in the place where they look natural. Take a marker and mark on the headband on either side of the ear so you know where to glue. Double check the placement, then glue the ears in place, when the headband is off your head lol just an idea, as it may hurt to glue them to your head. Im assuming that the headband will be black, so after the glue hardens, color it with a black sharpie to make it blend in. Then see how they look, hopefully theyre in the right spot since you double checked before gluing.