How to protect myself from lawsuits
Nafisa is correct. The more contact you have with other people, the more you are at risk of a lawsuit.
That being said, having an understanding of rights and responsibilities is helpful. Publishers put out some fairly reliable information on consumer and even simple business transactions, but that is not really a substitute for consulting an attorney before beginning negotiations for a significant agreement and before signing such agreements as well.
Still, regardless of your acumen or your lawyer's, it is simply not possible to know all of the law. Lawsuits generally happen because people disagree on the facts or the law. Sometimes they happen because the law is not settled and the disagreement is over what the law should be in a particular fact situation. Sometimes, people pursue lawsuits regardless of the law, because they believe that the law is contrary to justice or their Constitutional rights.
Being reasonable in your approach to life is a great aid as is being thorough in your research and investigation of anything. Trying very hard to see what others might think about a situation can help.
Preserve evidence (usually documents) for as long as it might be needed. Being able to demonstrate that you have your facts straight is an excellent way to convince others that they have no case.