"Be diligent to present yourself approved to God as a workman who does not need to be ashamed, accurately handling the word of truth."  (2 Timothy 2:15 / New American Standard Bible)

In order to understand the Bible properly, one needs to ask five questions as he reads:

(1)  Who is speaking?

(2)  Who is spoken to?

(3)  When is the Bible author speaking?  Is the writer speaking to people such as Abraham and Isaac who lived in the Patriarchal Age when God revealed His will directly to the fathers?  Or, is he speaking to the people of Israel who lived under the Law God gave to Moses at Mt. Sinai?  Or, is he speaking to people today who live under the Law of Christ, which is the New Testament?

(4)  What type of language is the author using?  All human languages have two types of speech:  literal and figurative.  The key to a correct understanding of any part of the Bible is to ascertain the intention of the author of the portion or book under discussion.  The Bible contains Poetry (as in the Psalms), Parables, Prophecy (Isaiah to Malachi), Letters (the epistles), Biography (the gospels), Autobiography/Testimony (Acts), Authentic historical facts (such as 1 & 2 Kings).  Thus, the author's intention with respect to any book of the Bible is usually quite clear from the style and the content.

(5)  What are the circumstances or conditions under which the writing is given?  The Christian faith is historical and evidential.  The Biblical text is best understood when one is familiar with the customs, culture, and historical context of Biblical times.

If one can answer these five questions correctly, it will help him to understand the Word of God clearly.  However, probably the most important way to understand Scripture is by the Holy Spirit.  In other words, because the author of Scripture - The Holy Spirit - resides within the child of God, he or she is in a position to receive God's illumination.  So, the illumination of Scripture ultimately comes through the ministry of the Holy Spirit.