There is a lesson that many conversion candidates and newly religious Jews are not told until they've made a fool of themselves: There are different interpretations of halacha, and it's possible for all these interpretations to be halachically valid and accepted. In other words, the modern orthodox, the "just plain orthodox," the chassidim, and the chareidi practice vary significantly, but they are all valid interpretations of Jewish law. (Of course, some individuals may say differently!) Depending on the issue, there is not only one "acceptable" way to perform a ritual act. We can respect each other's practice and learn from each other.
Rabbi Joseph Telushkin discusses this idea in his book Hillel: If Not Now, When?, describing a conflict two thousand years old.
From the Gemara (Eruvin 13b):
For three years, there was a dispute between Beit Shammai and Beit Hillel, the former asserting, "The halacha is according to our view," and the latter asserting, "The halacha is according to our view." Then a voice from heaven announced, "Both these and these are the words of the living G-d, but the halacha is in agreement with the school of Hillel."
But since both are the words of the living G-d, for what reason was the school of Hillel entitled to have the halacha determined according to their ruling? Because they were kindly and humble, and because they studied their own rulings and those of the School of Shammai, and even mentioned the teachings of the school of Shammai before their own.
In other words, if your rabbi says something that conflicts with a book you read, they are probably both "right" and valid answers. Books with halachic rulings/explanations are usually "strict" rulings in order to be "acceptable" to the greatest number of people. That doesn't make the book "more right" than community practice where you live or the practice of your neighbors. Your practice can be different from what a book says, and that can be just as halachically permissible. Rabbi Telushkin quotes radio talk show host Dennis Prager as saying, "One of the most important days in the life of a religious person is the day he meets a person of a different religion, or of a different denomination within his own religion, who is both a good person and intelligent."
The life lesson here: don't tell others that they have the halacha wrong just because you read a different answer somewhere else. Usually, you just look arrogant and ignorant of Jewish practice. When you encounter something unfamiliar, take a mental note and ask a halachic source later.
The lesson in middos: When we disagree with other Jews, we should respect the "living word of G-d" in the other opinion. Beit Hillel respected the rulings of beit Shammai and was humble enough to feel they could learn from their opponents.
The "trivia" lesson: As a general rule, when Beit Shammai and Beit Hillel disagree in the Gemara, we almost always hold by Beit Hillel.