I sometimes take (non-Jewish) friends to experience a service in synagogue. This post is a (incomplete) summary of the questions I get and my answers.
Should I stand up with the others? There are some places in the liturgy where everybody stands up (Kaddish, Amida, some others). It is proper to get up as well, out of respect. Also, if people sit down, do that as well (this is less of a problem). This only applies if (pretty much) everybody stands up or sits down. If only some people stand up or sit down, it is better to go with the majority.
What if I mess up? It is pretty common that people don’t know when to get up or sit down. Don’t worry. If you suddenly find yourself to be the only person standing, just sit down. Try to do it in a way that suggests, that you had a perfectly good reason to stand until then and everybody will believe it.
May I sing along? I see nothing wrong with that. There are parts where the chazan (prayer leader) sings alone, be sensitive to that.
Should I answer amen or take part in responsive reading? Answering amen in some places counts as if you have said the bracha (blessing) yourself. The rule is that you can only answer if you know what you are answering. As you probably don’t – don’t answer. It is ok not to stay silent.
Should I bow, take small steps back, shake, cover the eyes, etc.? I’d advice against it. It is ok just to sit/stand quietly.
Can I ask someone what is going on? Yes. Best thing is to ask right at the beginning if your neighbour could help you. In some communities they show the number of the current page somewhere or somebody announces it. Take care to select the right prayer book and know which of the signs/announcements refers to it. You can ask anybody, it is a very very typical question. If you thought you could do it alone and didn’t ask at the beginning and need help during the service, you can of course ask anytime. Be sensitive to the fact that people are in the synagogue to pray. If they seem immersed in some private prayer, do not disturb them. It really is also ok not to know what happens and just experience the environment. It is ok to sit there without a prayer book. It is ok to read something different than what the others read.
Why do they ask me if I am Jewish? For public prayer, you need 10 Jewish men (some Reform communities also count women). In a small community they might not yet have the ten and just want to know if they can count you. That’s all. Nobody will throw you out if the answer is no. So you need to be absolutely honest with your answer!!
Can I take an active part in the service? Short answer: No. You shouldn’t do anything that goes beyond watching and singing along.
What should I wear? For men: Long trousers and a shirt. Necktie and jacket are usually not necessary. For women: Try to cover ellbows, shoulder, collarbones and everything in between. Clothes should not be too tight. In some places women only wear skirts. If you do not have a skirt, you can try a longer top over looser pants. In general: Try to look neat and modest. “Business casual” is a good way to achieve that. Avoid political, religious or other statements (in text or accessories).
Can I/Do I have to wear a kipa, tallit or tefilin? Kippa yes, you have to. It is a sign of respect for the holiness of the place, it is not worn to indicate you are Jewish (in a synagogue, outside it probably would). Other religious items should not be worn by non-Jews. Politely decline if somebody is offering you something.
Did I miss something important? Tell me.