There is no trick that's going to work everytime. If there was, none of us would be here. If you try to apply a technique and it doesn't work, you're going to get annoyed and lose confidence. There are techniques that are going to help you in general, but keep in mind that using them only when you have a block is not going to help you. You would need to constantly practice them voluntarily over a period of time to get any results. Different people get different results with different techniques, so try them all and see what works for you. Some of them are prolongation, bouncing, airflow. In my experience, nothing really works when you need it the most. It's a slow process and it takes months of practice, learning from mistakes etc.