Yes,you can if your country allows that but most of the country doesn't allow this kind of actions because it will leads to money laundering the people who have black money they can convert it into bitcoins through you.But you are going to pay taxes for their money too.
But you don't need to open a shop for trading the bitcoin just you can do it in online by staying at home,try to think about it.If yiu think it is best thaen start yiur trading on localbitcoins.com.