Sin is addictive. That is, any sin one "tries" is likely to be repeated. Unless your conscience is strong enough to make you regret it afterwards, the rewards you perceive can overpower your dedication to goodness.
The saying, "Try it, you'll like it" is especially bad. If Satan is a snake, then "trying out" sinful behavior is like playing with baby snakes. The Bible calls Satan an "ancient serpent" and "a liar ... from the beginning".
The idea of speaking with "a forked tongue" illustrates the concept of tempting someone into sin by using words with double meanings. "You won't die," said the serpent to Eve. Yet God had told her that "In day you eat of the fruit, you will die." Although Eve lived long enough to mother at least three children, she "died" in some way when she ate the forbidden fruit of knowledge.
Young people can try to tempt their peers to try vices such as drinking or cigarette smoking in defiance of parents. "It won't hurt you," they say. But what they don't tell you is that alcohol and nicotine are addictive (see addiction). You can't stop merely because you decide to stop.
Fornication is also addictive. The pleasure it gives, despite being illicit, is highly rewarding. There is a world of difference between the person who has never had sex and one who has (see virginity). The idea of abstinence before marriage and fidelity thereafter is tied to the virtue of premarital virginity and the avoidance of the sin of fornication.
Once you start, it's very hard to stop. It's not like going to a bad neighborhood, where there is danger. Once you perceive the danger, you can easily make the wise choice of avoiding that place. With sin, the problem is overcoming the bad habit as well.