This verse seems like a fairly straightforward statement of a truth repeated in various ways dozens, if not hundreds, of times throughout the book of Proverbs. Those who practice righteousness will ultimately succeed, while the sinfulness of the sinner will be his undoing. The way Solomon composes this proverb, however, brings out a few particular points.
First, the emphasis in the first half of the couplet is not necessarily on the godly man's success but on the fact that his practice of goodness shields him from adversity (compare Proverbs 2:11; 4:6; 13:3). A practitioner of God's way of life is protected by the fact that he does what is right. If a person does good things, avoiding what is evil, he will be drawn into adverse situations far less frequently than those who dance on the edge of the cliff.
For instance, the Christian who lives by the injunction found in the seventh commandment—”You shall not commit adultery” (Exodus 20:14)—will not put himself or herself in tempting situations; and on the rare occasion that a temptation of that nature presents itself, he or she will, like Joseph, run in the other direction (Genesis 39:12). Such a person's righteousness—his right doing—guards him from the destruction that sin causes, and “the wages of sin is death” (Romans 6:23). We could also understand this to suggest that a person who walks uprightly shelters under the protection of God, who is pleased with those who practice righteousness (Colossians 1:10; Hebrews 13:16).
The second half of the verse communicates the exact opposite: He whose conduct is determined by sin is bound to fall into destruction. The sinful way of living offers the sinner no protection at all; the course of sin will run unchecked through his life all the way to death (see James 1:14-15)—provided that God Himself does not arrest it through His calling. This is the course of the world that we see every day on the street (Ephesians 2:1-3).
We can take this principle to the bank. Even though we see in various places in Scripture (for example, in Psalm 10), and even in our own experience, that the wicked seem to prosper, we can be assured that their prosperity is only temporary (Psalm 37). The evil that they do will catch up to them in time and begin to take its toll. The corrupt always pay the piper.
The Hebrew text contains a pair of technical oddities in this verse's second half, making it difficult to translate into English but bringing out a significant point. The oddities are that both nouns, “wickedness” and “sinner,” are abstract nouns in the original. The NKJV translators, as in many translations, chose to render only one of them as abstract, “wickedness,” and changing the other to a concrete noun, “sinner.” Literally, though, this part of the verse should be read as “wickedness overthrows sinfulness.”
The point this brings out shows just how pervasive sin is once committed. There is no such thing as a partial sinner; one is either righteous or sinful. In practicing sin, the sinner is perfectly wicked—he is sinfulness, nothing but sin, a mass of evil and corruption. James puts it another way, writing that if we break one commandment, we break them all (James 2:10-11). Jesus, speaking both to His disciples and to His audience of Jews, calls them “evil” (Matthew 7:11; 12:34). Paul writes of all humanity, “For all have sinned and fall short of the glory of God” (Romans 3:23). James states the simple truth that we all stumble (James 3:2).
Each time we sin, then, we become evil and require the gracious forgiveness of God through the blood of Jesus Christ to become clean once again. The lesson in this proverb is to make it our practice to do what is right and good in God's eyes, and that will greatly diminish our chances of falling into sin and straining our relationship with God.