The answer to this question will have the single biggest impact on how you approach starting an online store.
Is it a downloadable product? Is it a service customers can book? If you sell physical products they need to be shipped, and you need to work out how you’re going to do this and at what that will cost. Do you make your customers pay for shipping, or do you include the cost of shipping in your products and offer free shipping? Do you have the weight and dimensions of your products? Can you get this information from a supplier or do you need to get this information manually? Are you just shipping to certain areas, all of the country or even internationally? How do you handle shipping for product returns? These are all questions you need to have clear answers for, otherwise it can cost you a lot of money.
You also need to consider resources. Do orders need to be manually picked, packed and shipped? Can this be completed within your existing workflow or do you need new processes? When your website becomes very successful and you process hundreds of orders a day, can you still meet the demand?
How big is your range? There’s nothing to stop you selling thousands of different products, but that involves a lot of data entry. To start with you may want to focus on your core products and have an achievable plan to increase the number of products available online steadily over time.
You also need to consider whether you’re planning on managing inventory, customers, and accounts on your site or if you need to integrate with other systems. Getting different systems to exchange data can be very complex and time consuming.