Common and Local Markets

What are the benefits/disadvantages of trading on a common and locale market instead of an international one?

The main benefit is score. The more you buy/sell on local common market, or more self sufficient you are, the higher your score. The only drawback is you might not make as much off a product that is in short supply. But then again you don't spend as much on short supply items either

Hope that helps

I have a question about Common Market, if I want to start up one how do i that and start trading, please help me, thank you.