Be armed with at least three solid stories of your clients who weathered bad or volatile markets in the past and came out ahead using your advice. The reason your clients panic during market downturns is due to emotion, not logic. Don't try to console them only with logic, as they won't stay convinced. They can't remember the logic and are again consumed by emotion. That is why you should always use solid arguments followed with stories the clients can remember. If you can do that, you won't have to say the same things over and over to the same clients.
An effective time to ask for referrals?
At the end of the conversation, ask for referrals. I am sure the last thing you think of in a market downturn is to ask for referrals. It's like asking a car crash victim to buy life insurance while still in the ambulance.
Yet while most advisors don't even call their clients during downturns, you will be able to pick up more market share from clients who are terrified about losing even more money.