This is a perfect guide for any beginner to the world of email marketing. It can often be super confusing when you are new to email marketing and you may not be aware of how to go about things. This article is great as it talks about the various factors that can make email marketing campaigns a true success. I agree with every single point that has been mentioned above. I especially agree with personalizing emails as this can totally grab the attention of any reader. Thanks for this post!
Location: Businesses that offer local service, such as a lawn service company, obviously need to target local customers, but regional, national, and global companies can also benefit from location-based personalization. Consider running special campaigns for customers in a specified location based on regional events or what’s happening at your local office.
Part of the problem is that people are confused about the difference between ‘strategy' and ‘tactics'. It's essential not to get these two confused. They are related – tactics are a vital part of what makes a strategy work – but they’re not the "be all and end all." Too many people neglect a full and comprehensive strategy in favour of a bunch of loosely-connected tactics. So, to recap:

Messages which require online action work better in email than DM (direct message on social media), whereas calls-to-action to text to a shortcode or download a mobile app work fine within a DM. RFM and response analysis will indicate channel preference since customers with a preference for specific online channels will be more responsive in them and will make more purchases online.
This A/B test indicates that engagement is one problem, but your subject lines are an even bigger problem—and one you can solve right away. CTR rates are understandably lower among the less-engaged group, but you saw engagement increase with a punchier subject line, so there is room to improve CTR among cold leads. CTR rates are higher in the more engaged group, but with a better subject line, this rate could go through the roof.
Alternatively, at least, an eye-catching design. It’s worth letting a proper designer have a go at prettifying your emails. Customers are often opening emails on the go, so you need to work hard to grab their attention. Making your emails nice to look at is a brilliant way to hold their eye. Netflix put time and effort into making their emails stand out, personally and visually – and it pays off for them!