There is no best way, it depends on the purpose of your email marketing campaign. Usually you try to get 'more business' out of your email list. There are a number of commonly used methods that work well:
1. Try to segment
2. Personalization, salutation and sender with name.
3. Catchy subject / title
4. Correct frequency, software, email lists
The important thing is to A / B test your email format and content often.