Character Witnesses

Character Witnesses aren't Stars and they aren't Experts, but they still have information and you want to make sure that the jury doesn't doze off watching them. These need to be real people, but they should have a quirk or interest. For example, consider a scuba diver obsessed with Aquaman or an Aussie trying to save the Midland's Muddigger. It shouldn't be distracting, but it should be interesting, and, more importantly, it should be maintained through the direct and cross.

Expert Witnesses

Expert Witnesses can make or break a case. They have all of the official facts, but often times their affidavits are about as dry as the Dust Bowl. So when playing an Expert, its important that you tell us the facts but also make them interesting. You don't usually want to go full out character witness, but you also don't want to be boring. Think about that favorite teacher you've had. Not the one that you loved because you never did work, but the one that made you learn about history because you never realized that's what you were talking about. That's what you're going for. 

Star Witnesses

How convincing are you as a the strong but wounded father? What about a grieving mother? An ex-employee reeling from betrayal? What I'm really asking is, can you convince me to feel bad for you?
If so then, the Star Witness may just be the role for you. Just try to avoid melodrama. Sniffling into a tissue when you're off the stand is good. Loudly sobbing when opposing counsel says something you don't like isn't good. Work on the build up to the sob story, that way we can all get sad with you.