Commitment and consistency
Most people have a need to be consistent. If Maureen says she loves opera, she’ll feel more inclined to accept an offer of free tickets. Can you get your readers to make a small commitment that demonstrates their interest in your offer? Perhaps through signing up for a free trial or a sample package. These small interactions can help you lead customers to bigger purchases.
From Influence: The Psychology of Persuasion by Robert B. Cialdini