https://youtu.be/EJimTW9x9UA This is the video that got me in. Check his channel for more and search for "stuttering airflow" in Youtube, there may be other videos on this. In the original video it is said that you shouldn't force a lot of air out, only a little. But I often had to force almost all of my air out to say a word beginning with a vowel as they seem to be harder to pronounce. The more you practice, the less air you'll need to use.