This is a fertile source of information. Ask your librarian for help as well. Log onto the Internet. From looking up comparative product pricing to checking out a company's financial standing, odds are you can find most of the information you'll need with a few well-chosen searches on the Internet. Check with associations.
Many trade organizations provide biographies and directories of their members.
These materials can be a good source of information. Check with a stockbroker. Your goal is to learn as much about your opponent as you can before you begin negotiating. That will give you a much greater chance of finding common ground, developing rapport, and influencing your opponent to agree to a deal. Let's say you're being wooed by a company for a sales position.