You should always consult with a lawyer before you file a lawsuit. There are several reasons why this is a good idea, and a lot comes down to the fact that the legal system can be hard to navigate without professional help.
There are many, many rules in the legal system. These rules detail every aspect of a legal case. Just a few of the many examples of different rules that apply include:
These are just rules that deal with basic trial procedure. There is also a whole host of rules regarding what you need to do to actually prove your case. For the average layperson, understanding all these rules would not only be difficult and time consuming, but would be downright impossible without getting an extensive legal education.
If you are planning to file a lawsuit, you should seriously consider consulting with a lawyer. A lawyer can help you figure out if you even have a case, and if so, how to navigate through all the court rules so you can prosecute your case successfully and get the compensation that you deserve.