Since you can only control what happens before you hit the send button, try these steps:
Follow the golden rule of
email marketing: never send to anyone who did not give you explicit consent to email them. As I mentioned above, recipients are now conditioned to use the Spam button as a way of disposing of unwanted and unknown email messages.
Do not send to old addresses that have been sitting idle in some database. This is like going up to an adult on the street and telling them you were their preschool teacher and asking if they remember you.
Send regularly. Do not wait too long between messages, but do not send too frequently. Remember, the key here is to have the recipient recognize and appreciate your message.
Clearly identify yourself in the from field. Using your company or brand will get your message recognized, and hopefully opened.
The subject line needs to truly represent the message content, and should not try to trick the recipient into opening the message. Use the subject line in tandem with the from field to build brand awareness and highlight the value of the message content.