When going through my playlist, the ones I find more helpful are the slow monologues, which allow me to breathe in between pauses and take my time. Many actors have different sppech patterns, some are a lot faster than others. If possible stick to the slower speach patterns for the beginning. Remember to enunciate and open your mouth just as wide as the actors are doing so. Once you improve challenge yourself more. One that I found particulary helpful is this one https://www.youtube.com/watch?v=JU7tDawkr2Q&list=PLiOVBKjiaKkYXX8qwoWkZNN1pP9OrsdY8&index=5 Although you dont see his mouth when talking he has great enunciation and a decent speed to track with your own voice