Agreed on the eye contact. But knowing what your mouth is doing can be helpful in know what it should be doing. If you're trying to say the word "pants" and you can't get to the **a**, it can be helpful to understand what needs to happen to get to the **a**. You need to reduce the tension on your lips and open your mouth laterally as if you were smiling. If you're not doing that, having that as a mental cue can help you get to the vowel where you can confront it directly and work on not blocking.