To read the New Testament fluently in Greek is one of my ambitions, an ambition I am actively pursuing. The more I learn about New Testament Greek, however, the more I see errors and problems where people have relied on brief entries in Greek-English dictionaries in explaining certain Bible words and passages. This is especially true if older dictionaries are used that were written before the discoveries, in the late 1800s and in the 1900s, of numerous ancient papyri written in Koine Greek.
Even if the definitions in these dictionaries approximate the possible meanings of a given Greek word, they usually do not adequately provide a cultural or literary background as to how the word was used by the original speakers and authors. Even a phrase such as kalon ergon (which can be translated as “a good deed” or “a fine work”, etc) has a depth of meaning that may differ depending on the text and cultural context (e.g., Mark 14:6 cf. 1 Tim 3:1 NIV).
Knowing the dictionary definition of a particular Greek word and its grammar is useful but sometimes this is not enough information to give an understanding of how and why that word (or a phrase) is used in a particular sentence.
A dictionary definition does not always give the sense the author intended. It does not alert us to any rhetorical devices being used, devices such as hyperbole or irony. And it may not note the use of idioms. Moreover, information about the etymology of words, which is included in some dictionaries, can mislead people about how the words were used and what they meant in real life.
An understanding of the Greco-Roman culture and a knowledge of the literature and documents written around the same the time as when the New Testament was written are important in helping our understanding of New Testament Greek.
I love what Wayne Meeks says on this topic:
“. . . so simple a task as translating a sentence from an ancient language into our own requires some sense of the social matrices of both the original utterance and ourselves. When we take up the dictionary and grammar to aid us, we err unless we understand that they only catalog the relics of language as a fluid, functioning social medium. If we translate without that awareness, we are only moving bones from one coffin to another.”
Wayne A. Meeks, The First Urban Christians: The Social World of the Apostle Paul, Second Edition (Yale University Press, 2003), 5.
We need to be careful that our use of Greek dictionaries and other aids is truly helping us to see the living Word of God more authentically and that we are not using them to “move dead bones”.
Learning New Testament Greek takes a long time and is an ongoing process, and most people do not have the time or inclination to embark on this venture. But if you do want to find out the meaning of a Greek word, be aware that Strong’s and Vine’s are not reliable dictionaries. (If you do use Strong’s or Vine’s, or any dictionary, read the instructions on the first few pages about how to use them properly.)
Importantly, we should be careful not to be presumptive or pedantic about ascribing meanings and functions to certain words and phrases that may be unclear and ambiguous to modern readers.
I love reading the New Testament in Greek. The New Testament is more authentic and seems more vivid in the Greek than in the English, but I have to keep reminding myself to take it slowly and carefully, and not to rush to conclusions about definitions and interpretations.
It is no wonder that many Greek students are cautioned that “A little Greek is a dangerous thing”.
 Seumas McDonald has a tiny post about why we must read non-New Testament Greek to understand New Testament Greek here.
 If you can’t read Greek and want to find out the scope of meaning of a certain passage, read the passage in several English translations. I recommend the (1) New American Standard Bible, (2) the New Revised Standard Version, (3) the New International Version (2011), and (4) the Common English Bible. Most well-known English translations are excellent. And read the whole book or letter that contains the passage, looking for keywords and themes. Context!
 Strong’s Concordance (first published in 1890) is not always accurate. Strong’s is a wonderful work, but it was written and published around the same time as the numerous newly-discovered Greek papyri in Egypt began to be published. The newly discovered papyri have greatly helped us to better understand the Greek of the New Testament.