We have already talked about how to set up an online shop with the Printful API:
It is very easy to follow the instructions to create the process of designing and selling personalised (own brand) items.
Follow the steps and we give you some recommendations.
Develop your own brand. Using a brand allows you to get to work without copying problems. Using another system will always cause problems and will never be useful in the long run.
Generate the right price as an incentive to buy.