I am not sure but in my opinion it would be to offer a 100% guarantee.
In my opinion, give away products would be a sure way to boost sales.
When you give away a little quantity as a way to advertise your product, your sales may boost. Because your product will reach to the customers, and when they will use your product and find it good, they will advertise your product. They will tell their family and friends about how good your product is and in this way other people want to buy your product. This way you can boost your sales
