1. Discuss Authorship
When preaching from a certain book of the Bible, take the time to explain to your congregation some of the reasons why the church believes the listed author actually wrote the book. Or, if you are preaching, for example, from Philippians, share facts (such as New Testament Scholar Daniel Wallace contends) that "among NT scholars it is virtually unanimous Paul wrote the book." 
Also, if you are preaching from a book in which authorship is unsure of or undecided, don't be afraid to explain that. Then, when one of your parishioners hears an overblown claim such as the ones Bart Ehrman makes, they won't be blindsided, but informed and equipped to stand firm.
The Christian Apologetics Study Bible is a great resource that can will equip you to argue for traditional authorship and prepare you to discuss some of the challenges offered by skeptics against traditional authorship.
2. Offer a Resource
When you are preaching, you don't have time to discuss every issue you are addressing in exhaustive detail. Therefore, it can be helpful to offer resources for those in your congregation that might want to learn more about a given topic.
For example, if you are preaching from the Old Testament and come across a difficult passage involving OT ethics, offer a resource such as David Lamb's God Behaving Badly or Paul Copan's Is God a Moral Monster?. These resources will allow those in your congregation who struggle with such matters the ability to seek answers to their questions. You don't have to have all the answers, you just need to know where you can find them!
3. Share Archaeology
If you are preaching from a text that includes, for example, the Pool of Bethesda or the synagogue in Capernaum, show a picture of the location to your congregation. This serves to ground the passage in reality. It also helps the listener picture the historical event that occurred there.
Moreover, you might want to share with your congregation, when preaching from the Book of Luke for example, that scholar and historian Colin Hemer has identified 84 facts in the last 16 chapters of the Book of Acts that have been confirmed by historical and/or archaeological research.
You can find them here.
4. Share an Argument
When you are preaching, don't be afraid to share an argument for the existence of God or the reliability of the Bible. Some of these arguments can be given in a short, memorable way that could affirm the faith of your congregation and possibly challenge the listening skeptic.
5. Share a Video Clip
Ministries such as Stand to Reason and the One Minute Apologist offer short video clips with credible answers to some of the most difficult questions aimed towards Christianity. These videos can easily be incorporated into your sermons.
Courage and Godspeed,
1. Daniel Wallace, Philippians: Introduction, Argument and Outline, June 28, 2004.
Pastor Stephen J. Bedard on Apologetics in the Pulpit
Dayton Hartman on Pastors and Apologetics
Tim Keller, Apologetics, and Preaching