If it happens that you will need to explain Orthodox beliefs about something, I would be careful not to explain any more than they are willing to hear. If they close down or become argumentative, just stop. You are not obligated to give everything away, especially if they are closed to it, and debate is pointless. "Do not give holy things to dogs, and do not throw your pearls before swine."
And don't be afraid to say "I don't know", or "That is a mystery". There are many examples of mystery in our faith, and it's not something to run away from.
If you are able to give the Fathers' perspective on the verses of study, that would bring something to the table for everyone, I think. (If you know the topic or verses of study, you can read up on it beforehand.) In my experience, a Protestant Bible study is a lot of "This verse means to me..." If you can share the ancient Christian interpretations instead of your own, some may be open to hearing it.
Let us know how it goes!