The Theological Dictionary of the New Testament is one of the finest. For a concise understanding of the Greek this set of books is a must for your library. I know that you will be glad you made the investment. I know I am.Once you use these you will never want an Interlinear.
I have used "Kittels" with profit for over 30 years. It is sometimes exhausting in it's depth, and is sometimes difficult to unbderstand if you are not careful. Believe it or not, it does not cover all biblical NT words, and so the large Liddel/Scott is nice to have. But as always, when you use it take local context into view, and it is of profit. See the section on Baptism if you have a copy to review, it will underline what I am saying.
The only set of books you will need in your library. I have been in ministry for over 23 years. I have read lots of books; commentaries and history books and these, by far, are the best I've used in training for my life and ministry. I study the scriptures to live by them and not just to teach to others. These books have helped me dispel myths and erroneous teaching I received in the past and gave me a better understand of the scriptures. I recommend these to pastors and laymen alike - I believe in theological studies as a lifestyle and not just of the preacher.
No serious Biblical scholar should be without this set. It is not only one of the best theological dictionaries that is available today; but it is THE best. One will understand the full meaning of the vocabulary of the New Testament as each word is traced back to its root meaning sometimes beyond the first New Testament appearance. The articles are excellent, and many contain more information than found in first-rated commentaries. Take for example the word agapao thirty-four pages of solid exegesis, or the word Theos forty-four pages of clear sound exegesis. The pastor will be blessed by these volumes as they will open a new world to him, and so0 will the lay person benefit, for these volumes contain a goldmine of information. I found the volumes very useful and helpful, and I use them constantly in my study. I very strongly recommend these volumes to everybody lay or scholarly. Go out and purchase them, especially with the price CBD are offering, and you will never regret it.