One of the surest ways to lose credibility with the judge and any lawyers involved in your case is to use the wrong legal terms.
I'll give you a pretty common example of how pro per (basically the same thing as pro se) parties use thw wrong language.
When you want to ask that the judge delay a hearing or your trial you normally file a Motion for Continuance. So the proper term is that you file a Motion for Continuance then, at the hearing, you move the court to grant the motion. In simpler terms, a Motion is filed and the court is Moved to grant it. Nothing marks a beginner like saying "I motion the court to grant my continuance".
Another mark of a beginner…quoting from Black's Law Dictionary. Don't rely on the Black's Law Dictionary for anything other than a reference tool. It is great to look up words that you're not familiar with, and is a common gift to many people entering law school. However, it has no legal authority and I don't know any lawyers who actually use it after the first year of law school. Most terms that are going to be at issue in a case are either defined by statute or by case law.
What's the best way to learn the legal lingo? Go to court and watch lawyers. Watching television or reading John Grisham novels isn't the way to go (even though his books are very good, they're still fiction and he takes some artistic license with the way things really work.)
Even better? Don't use legal jargon. Explain what you mean in plain English. That way there is no chance of you slipping up and mispronouncing something or using the wrong term. Lawyers say voir dire because it is what they are taught to say in law school and then in their first job. The term jury selection means the same thing so why bother?