Make sure you have a registered trademark, patent, or copyright prior to bringing a lawsuit.
You have paid all applicable renewal and government fees to keep your intellectual property rights active.
Look at all available public sources to make sure you have enough support to bring a lawsuit and it will not be seen as frivilous. Identify the name, address, and contact information of the defendant that you want to sue. (It is hard to sue companies that you cannot locate).
You have gathered and forensically preserved all emails, documents, and evidence you need to make an allegation of infringement.
Lawsuits are costly, and often there are more simple ways of solving a dispute. Will a simple phone call help? What about a cease and desist letter? Is there a business solution that can more easily achieve what you want? Have you considered mediation or private arbitration?
If the above points leave you with more questions than answers, you should consult with a licensed attorney. SueEasy offers 1 hour consultations with an attorney for $300.00.