Most people don't think of email as a lead- or contact-generating channel. But because people forward helpful emails to colleagues or friends, it can actually expand your database if you simply make forwarding or sharing email content easy for recipients. Include calls-to-action in your emails that make sharing an obvious choice for recipients, particularly with your most useful assets.
Did you know there are organizations dedicated to combating email spam? Thank goodness, right? They set up a little thing called a honeypot, which is a planted email address that, when harvested and emailed, identifies the sender as a spammer. Similarly, things called spam traps can be created to identify spammy activity; they're set up when an email address yields a hard bounce because it's old or no longer valid, but still receives consistent traffic. Fishy, eh?
The ideal type of opinion (unrelated to your expertise) is one that doesn’t offend anyone, but makes some people relate to you more. For example, I’m a vegetarian. I used to protest whenever there wasn’t a big piece of meat on my plate. But when I tried eating just veggies for a couple of months, I realized I felt a lot more energetic. Sure, it’s more ecological. And often animals are treated cruelly. But those aren’t the things I emphasize if someone asks why I’m a vegetarian. No one in their right mind has a strong negative reaction to someone eating food that makes them feel energetic, right? But for some vegetarians it’s a very meaningful choice, so it might have a positive impact on those people. That said, I highly doubt that my choice of diet have any direct impact on my sales.