There are many things to consider when selling new LEGO sets on Amazon and eBay. The first thing to think about is whether or not you will be selling the LEGO sets as-is, or if you will be opening the sets and selling the pieces individually. If you are planning on selling the sets as-is, you will want to make sure that you are comfortable with the LEGO set's packaging being opened, as this is typically required by Amazon and eBay in order to verify that the LEGO set is complete and undamaged. If you are planning on selling the pieces individually, you will need to take into account the time it will take to carefully open the LEGO sets and sort the pieces by type and color.
Another thing to consider is the price you will be selling the LEGO sets for. It is important to do some research on Amazon and eBay to get an idea of what similar LEGO sets are currently selling for. You will also want to factor in the cost of shipping the LEGO sets, as this can vary depending on the size and weight of the sets. Once you have an idea of what you will be selling the LEGO sets for, you can start listing them on Amazon and eBay.
If you have any questions about selling LEGO sets on Amazon or eBay, you can always contact the customer support teams for both platforms. They will be able to provide you with more information and help you get started with selling your LEGO sets.