Rod Decker provides A Recommended Bibliography for Beginning Greek Students. He lists different kinds of books (texts, grammars, lexicons, concordances) etc. by year of study. For a third year student he recommends as a lexicon the following:
Liddell & Scott (the standard lexicon for classical Greek; it does include NT material). “Liddell,” BTW, is pronounced “little” (not “li-dell”).
The surname of the co-author of this lexicon, Henry George Liddell (the father of Alice in Wonderland, believe it or not), is given the pronunciation /ˈlɪdəl/ by Wikipedia (at least it did when I wrote this) not /ˈlɪtl̩/. I was puzzled by this apparent typo before I realised Decker is relying on the voiced American T.