It depends on what and how you are selling. Many retailers are doing profitable business but in my opinion, e- commerce is best from cost and ease point of view. I would suggest to watch this video to understand more about this (https://youtu.be/uv87Sa8JP20?feature=shared)

There are a lot of opportunities to start a business in this investment. You can select by doing research on the internet and by asking people. However, whatever you do, please try to get as much knowledge as possible for that domain and if possible, do an internship or job in that industry so that you know all the process of that particular business