In my opinion, free shipping will satisfy everyone from your campaign. However, coupons and promo codes will make your customers delighted. You have to make great deals and coupons for them so that you will have a lot of clients. People enjoy when they see sales on the thing they want to buy. By the way, if you want some coupons or promo codes at different companies, well, I recommend you to use
https://almowafir.com/en/. Recently I`ve bought some clothes, and I save up to 30%. This is a nice feature, which makes clients delighted. I recommend it.