People who know what they're talking about
Richard Heimberg, Debra Hope, and Cynthia Turk are renowned experts in Social Anxiety Disorder (SAD). They developed a proven step-by-step program to overcome SAD at their clinics. Check out this blog for a list of the clinics.
Managing Social Anxiety is a self-help workbook that is best used in consultation with a therapist or anxiety coach, but can be used on your own.
To find a therapist or coach, check out this article on ways to find help (in-person and virtual).