The Lindamood or LIPS program is often used by speech therapists to help students understand what your mouth and breath should be doing when saying the letters. It is often done with a little hand mirror nearby. For example, the letter "H" has air exhale while sometimes the "K" sound can inhale (especially if you are a singer) or exhale. Most kids have "R" articulation issues.
As a reading specialist, I've used parts of this program with struggling reading working on phonemic awareness, or with English Language Learners who are comparing first and second languages. Our "E" is different than the spanish "E."
If you are interested in learning more, ask your local speech teacher. They are fountains of untapped support for the early reading teacher.