The easiest way to know about the operations of different companies would be through the power of the Internet. So whether you are looking for information about an individual belonging to a particular company or for general information about the company's operations globally, you will be able to find everything online through relevant websites that carry appropriate information specific to the country that the company that you may be investigating about may be from.
The Internet is the easiest of ways to research about anything otherwise you would be spending days waiting for third party sources to come up with appropriate due diligence reports for you which is also one of the best ways that you will be proceeding as they may have other sources of verifying information and detailing things out before presenting them to you.
If you are looking to do business with a particular company for example, then you will have to research about not only the company itself but also about its founders and executives so you get to know who you are going to be dealing with. For instance, you may want to get information about Andreas Zivy of Ameropa if you are looking to have business deals with this Swiss agribusiness.