1. Have a good Bible.
Every Christian needs a good Bible that they can easily read and enjoy. A translation such as the English Standard Version (ESV), the ESV Study Bible is very well done, or the New International Version (NIV) is preferable as your primary reading Bible, although there are many other translations that are also quite good (e.g., New King James Version, New American Standard Version).
2. Have some good Christian books.
If you want to build a reference library, the first book you should buy is A Commentary and Reference Survey by John Glynn by John Glynn. That book will tell you which other books are the best resources available for in-depth Christian study and anyone who is serious about studying should have a copy of this book.
3. Have some good (free) online study resources.
There are many great websites that can help you do Bible word studies and such for free. Good examples include the following, with the first one built and run by Mars Hill elder, Zack Hubert:
ReGreek specializes in word studies from the Bible ‘s original languages.
Crosswalk has many translations and Bible study tools.
Bible Gateway has many translations and Bible study tools.
CCEL has most of the major works from Christian history for free and a “Study Bible” feature that pulls up historical church commentary on specified verses.
E Sword has numerous Bible study tools.
4. Have some good Bible software.
If you can afford it, Bible study software provides some amazing resources and companies like Logos Bible Software are worth considering.
5. Have some good websites.
There are many great resources available for free on the web with articles, books, blogs, podcasts, vodcasts, and MP3s. The following are some recommendations:
Desiring God is the website featuring a large repository of sermons and articles from my friend, Dr. John Piper.
Covenant Seminary has a “Free Downloads” link on their front page that will enable you to listen to hundreds of hours of their class lectures on many areas of Christian study. I am grateful to my friends at Covenant who have given the church such a gracious gift.
Mars Hill Church is where hundreds of hours of my teaching is available for free and has been the number one podcast on iTunes for religion and spirituality.
carm has good articles on cults, world religions, and apologetical issues.
equip.org has good articles, book reviews, and more, on cults, world religions, and apologetical issues.
www.christianitytoday.com/historyhas some great articles on Christian history and biography.
www.monergism.com has an almost overwhelming number of free articles on nearly every theological issue from a Reformed perspective.
6. Have some good community.
Most of the Bible was written to communities of people and is therefore best studied in community with other Christians. For this reason, getting plugged into a Community Group and/or taking midweek classes in addition to regularly attending a Sunday church service is essential.