Step 1: Contact a sleazy supplement seller. Lots of them are paying for reviews on Craigslist! Or just type "Garcinia cambogia" into the Amazon search box (or "green coffee bean extract" or "raspberry ketones" or "branched chain amino acids" or the name of whatever snake oil is popular this week).
Step 2: Write a 2-line "review" of an unrelated product, preferably a health- or fitness-related product. Be sure to include a link back to the supplement in your "review."
Step 3: Post a couple of other reviews. You know, 'cause it will TOTALLY make your account look legit. (Not. But please, keep fooling yourself.)
Step 4: Repeat a couple of times.
Step 5: Watch the bot votes ROLL IN! These folks did it and SO CAN YOU!