Note: Before continuing, please understand that what I describe below should not be interpreted as medical advice or treatment. This is just a summary of what I was told to do by my doctor and physical therapist. Please consult a physician or physical therapist for proper diagnosis and treatment.
The following stretches and exercises really helped me out:
1. Ecentric Calf / Heel Drops
As you can see, with a combination of treatment and very simple stretches, Achilles tendonitis is very treatable. In my case, it took 4-5 physical therapy appointments plus daily 15-20 minute workouts to fully alleviate my tendonitis.