* If you enter a shul on the Shabbat, be prepared for such greetings as “Gut Shabbos” or “Shabbat shalom.” Either is fine as a response. On Jewish holidays, prepare such greetings as “Gut yontif” or “chag sameach.”
* Understand that most Jews and most Orthodox Jews have no interest in getting non-Jews to convert to Judaism. I think this is a beautiful thing, but whether it is beautiful or ugly, it is a fact. So govern yourself accordingly. Don’t expect to be welcomed and embraced. Don’t think of yourself as a prize to be captured. Don’t start asking questions until somebody has indicated that he welcomes your questions.
* No matter how prepared you are to step foot in an Orthodox shul, you’re going to stick out. Most people will ignore you. Some people may question you. Don’t give more of an answer than a person has asked for. Many prospective converts are just brimming over with desire to discuss their conversion and unload on unsuspecting Orthodox Jews who have little interest. So don’t unload or unburden yourself with people who are not that into you.