Interested in visiting a local temple, best practices for me to follow?

TW: brief mention of the Holocaust

Good evening, I (24F) have been interested in taking classes and learning more from a synagogue/temple for a few years now but would like to ask how to best approach the topic?

Background: I grew up in a Christian household, but my grandfather (maternal side) is 100% Ashkenazi Jewish. He is still practicing Jewish and he and his family was involved in the Holocaust. My mother grew up in the Soviet Union, and was not raised Jewish. Therefore, I was baptized Russian Orthodox as a child (my father is Christian, but does not attend church often and did not grow up heavily religious). I was raised going to Jewish summer camps and after school activities (JCC, or Jewish Community Centers), and have some knowledge of Judaism and traditions. My grandparents still have dual citizenship for the United States and Israel and I have been fortunate enough to visit Israel 4 times. As a child and as an adult I have had friends who were Jewish, I have attended bar/bat mitzvahs, but I feel that I do not know where to start or who to ask.

I have wanted to learn more about my own Jewish heritage, and about Judaism as a whole but I am afraid of coming across inconsiderate or insensitive. I would like to attend adult classes at a local temple (Reform Judaism). Should I email or call first to express my interest? Should I try to visit in person as a first step? Is there a dress code I should follow when visiting, and should I not attend services? I am not sure where to start in the process and would like to know if there are certain things I should not do or say. I have done some internet research as well over the years, but I would like to ask for advice as well. I appreciate if you do read this post, and I sincerely apologize if I come across inconsiderate in any way.