My name starts with a P and what helps enormously for me is doing a hit and hold (technique from the McGuire Programme) on the P. You basically prolong the P sound like P-fffff. Before I was always getting stuck on the P, where I close my mouth and stop the airflow. This technique helps me to keep the air flowing and not get stuck for 90% of the occasions. For the remainder 10% where I still get stuck it is either because I am not focussing enough, have not practiced enough, or the pressure is really, really on.