You might wonder how reading the New Testament in Greek could possibly be useful. You quite rightly recognise that you will never be better at Greek than the translators of a good English translation. Even if the translation isn't great, you have a selection of commentaries written by experts, not only in the language, but the book in question. What benefit can there possibly be to reading a passage in Greek?
Well, here's one example: the parable of the wise and foolish men, with their houses on the rock and on the sand. I read the parable today in Matthew 7.24-29.
If your experience is at all like mine, you will have heard someone speak from this passage along the following lines. "If you follow the words of Jesus, you will be preserved through the storms of life. Temptation may rage at you, circumstances might make you feel like you're in the middle of a raging flood, but you will stand firm on the rock of the words of Jesus. But if you don't follow the words of Jesus, you will be swept away in the storms of life. You will be destroyed by temptation, or swept away by dreadful circumstances."
The idea is that Christians are encouraged that their life is secure—they are on the rock during the storms of life—and non-Christians are warned that despite appearances, their life is insecure without Jesus.
Reading Matthew 7.24-29 in Greek will help you avoid repeating this common exegetical blunder.
What jumps out at you straight away in Greek is the unusual verb, in an unusual form, that starts the parabolic story: ὁμοιωθήσεται. The verb, ὁμοιοω, means to make one thing like another, and here it is in the future passive, so a first guess at translating the phrase would be "he will be made like a wise man". Unusual forms are generally worth looking up in a lexicon, and as an extra encouragement to do so, we might notice that English translations tend to have "he is like" or "he will be like"—in other words, they have lost the passivity of the verb. It seems unlikely that the translators would do this capriciously, so there is likely to be something on the future passive of ὁμοιοω in BDAG (the lexicon).
BDAG glosses the passive with an active meaning, and specifically mentions the Matthean usage of the verb, referencing an article by Don Carson: NTS 31 (2), 1985, pp. 277-282 (you will need to be on a subscribing institution network to read the article, unless you pay for access).
Carson's article shows that the future of ὁμοιοω is used in Matthew to point forward to the day of judgement. Parables introduced with that form of the verb, then, tell us of the consequences at the day of judgement of our behaviour now. (Less convincing, in my view, is his argument for the passive deponency of the verb.) This is quickly confirmed by looking at a good commentary (sadly, of all those I own, only Davies & Allison cover the issue), and there's a nice verbal link between the rotten tree which is chopped down (ἐκκόπτεται) and the foolish man's house which is struck (προσέκοψαν)—a play on the same word root.
Notice how different this is from the normal application of the parable. The issue at stake isn't survival as a Christian during this life. The issue is eschatological security or destruction.
The storm that is coming is not life, but the return of Christ at the last day to judge the world. The torrential rivers, the rain beating down, the winds howling—these are all images of the coming judgement. Those who do what Jesus says will be made like the wise man, with his house on the rock. Those who do what Jesus says will be secure. But for those who do not do what Jesus says will be like those in the middle of a storm whose house is struck down by the storm, exposed to the awful hurricane of judgement with no defence, with nothing to protect them.
Of course, this fits in with the context too: vv. 15-20 have the illustration of the good and rotten trees, and vv. 21-23 have the explicit teaching of Jesus on false believers. Just as the good and rotten trees can be distinguished by their fruit, so now the wise and foolish men are distinguished by their actions in response to the words of Jesus.
You might think that it's possible to obtain the same exegetical result by reading commentaries, but there are two problems with that idea.
The first problem is that, sadly, most commentaries are on the English text and so miss the point (France's Tyndale commentary, for example, notices the contextual argument for an eschatological interpretation, but still gives weight to the "storms of life" idea). This is not to criticise the English translations: the only way to express the idea in English is "he will be like", or perhaps "he will be made like" (if you want to avoid recourse to deponency). That is the correct English translation—the problem the translator faces is that they can't flag up that in Greek, it's an unusual expression of an idea. The translation is correct, but commentaries often fail to give you the extra insight into the Greek text that you want.
The second problem is that even if you pick up Davies and Allison, you now have a several thousand page commentary in your hands. When you are pressed for time, are you really likely to wade through the vast amounts of commentary for the one exegetical insight you need here?
To me, the great advantage of reading in Greek is that real, important exegetical issues such as this jump out at you. You don't have to wade through a commentary. You just have to read the text. Instead of facing a horrible chore of wading through commentaries, finding the significant points is an exciting, enjoyable part of reading the word.