Successful email marketing requires you to have accurate research data behind all you do. How you talk and write to them as well as what you say can be gleaned by research on your niche. There is a person who finally cracked the code with how to communicate to her list of email subscribers. Since there is a lot of misinformation in her niche, she always has to clarify everything to people. When talking about investing, it is hard to do that and keep the email short. That is how she figured out her list, and she has done very well with her little niche.
Along the lines of building relationships, that is what the personal type email copy can do. Some marketers ask for the first name while others do not during the optin process. If not, then make sure you write using the personal, you, in your copy, and if you can weave an appropriate and relevant personal story, then by all means do so. Let's mention the power of story, and they can be very powerful and accomplish almost anything. Think about the fact that stories as a device have been used for thousands of years, and they are still used in almost everything today.
One very huge no-no for almost all audiences is the use of swearing in email copy, and that is a fast way to make some people leave your list. For example, if your audience is made up of professionals, then they like to keep things fairly professional because they like to feel that way. Once you know how to talk to them, then keep it like that and do not give them surprises such as a radically different tone. On the other hand, you would not want to commit the blunder of writing like that when you should not do so. If you have to be very formal and proper, then by all means do what you have to do.
A very important thing that you need to keep in mind as you are creating effective and successful emails is the relationship that you share with your subscribers. You can depart from many standard conventions if they really like and value what you offer. Here is a great example, Matt Furey has been making millions on the net for many years. When you see his emails, you might not automatically assume that he's so successful. He has a tendency to compose really long emails that are made up of really short lines but his readers, customers and fans really love him. Furey is now thought of as one of the absolute best email copywriters to ever write a line of email.