There are many signs or clues to dyslexia. However it is also important to be aware of the misconceptions or myths. Here are several websites that highlight some of the more common ones.
My Dyslexia Help Success Starts Here by the Regents of the University of Michigan
Myths (and Truths) About Dyslexia by the Yale Center for Dyslexia and Creativity
Myths by the Bright Solutions for Dyslexia
GAAB Lab Dyslexia Myths