I can only answer what you specifically mention, but. 1. The subject line is indeed more important than ever in emails, given how low click rates are (but that doesn't mean the body of the email matters any less than before). 2. You should always strive to write the best content you can produce. That's never not been the case, though obviously there isn't one objective version of what "best" means - it depends on an array of variables. 3. Never pay for links. If you want to pay anyone, pay a PR pro to help you craft an idea to pitch to targeted media people. It's expensive, and sometimes doesn't work, but when it does it can be very powerful. Mass spamming for links. it can work, but SEO fundamentals is a better investment of time and energy in my experience.