If your intellectual property is infringed:  In most cases, the first step is to gather information about the infringing activities.  You should seek to determine who is committing the infringement and how long the infringing activity has gone on.  If possible, you should try to get a feel for the amount of sales of infringing product, the infringer's market share, and financial viability of the infringer.  Such information will be important in determining how to address the infringement.  The next step is usually to select and retain an attorney, and/or discuss the infringement with your attorney.  Generally speaking, unless the infringer voluntarily ceases infringement, the only way to stop the infringement is to bring a lawsuit.  Your attorney should be able to help you evaluate the financial obligations of taking actions against the infringer versus the chances of success and recovery. 

If you are charged with infringement:  In virtually all cases, you should take action to respond to the allegation of infringement.  Do not ignore a charge of infringement.  Determining the proper course of action may take considerable time, so it is best to take initial actions immediately.  First, you should gather information about your accuser and select and retain an attorney.  Your attorney should be able to help you evaluate the financial risks and the chances of being found liable.  In most instances, you or your attorney will want to examine public records with regard to the intellectual property in some detail, and it may take some time to obtain the relevant public records.  In many instances, additional information about your own activities or the activities of your employees will also be necessary to evaluate your position.