open the bleeder screw just enough to see wetness start to form in the hole, then compress, the barely opened bleeder will allow the fluid to squirt out when compressing the caliper but isn't open enough to let too much run out and trap air in the system. You can put a small hose on the end to catch the squirting fluid also. This works well with ABS equipped vehicles to prevent the fluid from pushing back up into the ABS system.