I know it might seem counterintuitive, but talking to your audience like they’re an old friend will get a much better response than trying to sound overly-smart, super professional, or just stuffy in general.
Put yourself in the position of your audience. If you received a daily email from someone that was strictly facts and figures, big words, and no personality, how long until you started ignoring those emails, or even unsubscribing from the mailing list? Sooner than later, I’m willing to bet.
However, if you got daily correspondence from someone who spoke casually to you as if you had known each other for ages, wouldn’t you be more likely to read that message?
When you communicate with your audience in a conversational, humorous manner, they will bond with your persona and become much more invested in your relationship. They will think of you as a friend, not someone who is just trying to get money from them. They will come to value your opinion, interact with you (such as answering surveys, etc), and continue to engage with your emails.
This holds true for when you ARE actually trying to sell them something. Pitch it to your audience like you would tell your best friend or relative about this new product that you think would really help them out. That means explaining how you use(d) the product, how it worked for you, something funny related to the product, or anything that makes it seem less like a sales pitch and more like a friendly suggestion.
Think less like a company, and more like a human. It will help your bottom line immensely!