The Dummies series of books have been hugely successful guides to everything from fixing computers to learning languages although they’ve recently started to publish self-help books on psychological themes.
Unfortunately, they don’t fit quite as well into the general theme and hilariously, one of the titles is called Building Self-Confidence for Dummies.
UPDATE: Some great follow-ups grabbed from the comments (thanks skagedal and OmegaSupreme!):
There’s also the “Complete Idiot’s Guide” series, they have the similarly wonderfully named title “The Complete Idiot’s Guide to Enhancing Self-Esteem”.
Troy McClure in the Simpsons had a self help video called “Get Confident, Stupid” !
Link to book details (thanks Catrin!).