1. Slow down your speech. Actually, you can speak as quickly as you wish, as long as you are pronouncing every sound of every word and you are following the rules of good stress and melody. You will notice that newscasters often speak quickly but clearly. If you cannot do that, you need to practice. Meanwhile, slow down!
2. Make sure your articulators fully touch. What are your articulators? Your lips and your tongue – the parts of your mouth used to create sounds, specifically consonant sounds. Don’t get lazy and don’t allow them to touch only half way. For example word “general” if said quickly and in a lazy way can be very unclear. The sounds, N R and L in the word “general” require the tongue tip to be in the front for the N, and then curled back for the R and then in the front again touching the top of your mouth for the L. That’s a lot of work! Good speakers do that quickly and correctly. If you practice your tongue will get stronger, and some of these difficult sounds will require a lot less effort to produce.
To learn the correct mouth movements of the most difficult American English sounds, you can get my DVDs, “American Accent Course – 50 Rules You Must Know.”
3. Dont’ stop practicing!! Read aloud every day for 20 or 30 minutes. Record your voice. How does it sound? Are you pronouncing every word clearly or are you mumbling?