Of all Amazon assistance services offered by the freelance market, advertising assistance is the number one service purchased by sellers. Amazon advertising is vital for most products to succeed on the platform, and it is impossible to avoid if you're to enjoy any percentage of your product's potential market. It's also the easiest Amazon service to reduce your profit margin accidentally, without realizing it. More than any other service, PPC advertising requires knowledge and experience to utilize successfully. You can't do without PPC advertising, and you absolutely don't want to participate without experienced expert advice.
Amazon PPC Management
As a flexible rule, Advertising costs should be maintained at 22% ACoS or less, on only those ASINS chosen for promotion, and should not accede your planned Ad budget, or a maximum of 10% of the total volume.
In order to break this unwritten rule, on or off of Amazon, profit result, fewer costs, must significantly exceed ad spend. Losing track of these numbers is a common error in Amazon advertising.