Your "leads" or potential clients are not going to understand some of the industry terms that you might use during your presentation, so they are not going to know what questions to ask.
They are not going to want to look stupid, so don't expect them to ask you what a certain word means.
Here's what I would do:
1) avoid jargon - don't use big words that the average person won't know
2) stay on message - answer every question in terms of how your system or trading rules would perform
3) take a breath and take your time - it's better to take a beat and put some thought into your answers, than be rapid-fire. It's not a race.
4) "I don't know" - you'll gain a lot of respect if you have to say "I don't know, but let me get back to you in X days." You might have to research something or double-check on an idea before you open your mouth. It also gives you a specific reason to follow up with them.
Don't let curveballs throw you and take you off on tangents. Focus on your trading rules while your trading, and when you're marketing.