NOT for everyone

Customer testimonials aren't for everyone. Advisors with securities licenses are restricted in their use of testimonials, according to FINRA and NASD rules, so know the regulations if you are so licensed. This is from a FINRA FAQ: FINRA member firms may use general client endorsements or testimonials, such as a statement regarding the quality of customer service
or the accuracy of trade executions in communications with the public. If a member wishes to use a testimonial regarding the quality of investment advice provided to the client, then the member must ensure the communication complies with NASD Rules 2210(d)(1)(D) and (d)(2)(A) regarding testimonials.
Stray into the technical aspects of investing and the use of testimonials is even more regulated. Even if you aren't securities licensed, check with all the appropriate regulating bodies to ensure you don't unknowingly cause an infraction. For those of you able to use client testimonials, they are a great tool.