Chip Heath and Dan Heath in their book Made to Stick: Why Some Ideas Survive and Others Die discuss a principle called the Curse of Knowledge. The Curse of Knowledge is the difficulty of remembering what it was like not to know something. The importance of this principle is massive as we think about reaching people for Jesus. Here are some questions or practices that can help you fight the Curse of Knowledge in your respective place of service:

• Do you regularly connect whatever passage you’re preaching to the overarching message of the Bible? For me, this would be connecting it to the person and work of Jesus. For Paul, biblical preaching was always in some form or fashion Christocentric. Non-Christians (and Christians for that matter) are not going to make the connections to the overarching theme of the Bible; you need to remember this in your preaching.
• Do you define and explain words Christians regularly use? For example, words such as gospel, salvation, redemption, adoption, sanctification, repentance, belief, etc., are words that need to be explained and reexplained. I promise you, the people listening to you preach are not as familiar with the Christian verbiage as you think they are, let alone non-Christians. 
• Do you make it a practice to present the good news of Jesus Christ in every sermon? If the aim and hope for every person is to be reconciled to their Creator, then should you not make an appeal for non-Christians to repent and believe in Jesus and remind Christians to continually rest in the finished work of Jesus?
• Remember, we’re living in a country that is increasingly secular. Thus, most individuals do not hold the values and beliefs you think they hold; their lives are more and more removed from the Judeo-Christian values and beliefs. As you preach, you need to be mindful of this and be prepared to explain the logic and rationale behind being a believer and follower of Jesus, as well as show the inconsistency of their values and beliefs and of course do so in love (Eph 4:15).
• Have you ever stopped and thought about all of the “hurdles” that a guest jumps through to actually make it to a service? It would serve you well to remember the extraordinary feat that it is for a person who isn’t “churched” or someone who is but unfamiliar with your context or facilities to actually show up on a Sunday morning.

There are a multitude of others applications to this principle — what else would you add?