The best form of advertising may be no advertising at all. Referral Marketing provides the best return as it provides social proof and peace of mind for the new prospect. Reviews and testimonials from real people who have had positive experiences with your product or service is 100 times more valuable than any paid advertising. I only use paid advertising to create awareness of my company with a wider audience, and I advise my clients to focus on delivering outrageous customer service and gather as many testimonials as possible so we can leverage those in future marketing campaigns.