To grow GMV on other marketplaces quickly you’re going to need to do the following and do them well at a fixed cost that doesn’t change month to month.
Ensure you’re using listing tools that leverage your time and sanity when it comes to product listing
Ensure your customers have a consistent experience across every channel
Ensure orders are delivered on time and are exactly what the customer expects
Ensure you know what growth is going to cost you - no surprises