It is advisable to familiarize yourself with the views and opinions that your expert witness has expressed in previous cases for two reasons. 1) Earlier opinions may serve to strengthen your case and 2) opposing counsel may ask the expert about these opinions. For example, the medical expert witness may have relevant experiments, exhibits, case studies, etc. from earlier cases that may affect their testimony. Questions you will ask on direct examination should be rehearsed with the expert and you may want an associate to cross-examine them. When dealing with difficult subject matter, have the expert review how he will explain technical concepts to the jury.