First Seder - help?

Hi everyone,

I have been considering a conversion to Judaism for years, but I have moved around a lot and want to be in a more stable place so I can devote myself to a community when I convert, so I haven't formally taken that step. However, I have studied up quite a bit, so I know the basics (in this case, I know how the Haggadah goes, what is eaten, the customs, etc). A very sweet friend has invited me to join her family's Seder this year. I am very happy to be invited. What are some rules or etiquette a non-Jewish person might not think of? Anything I should do or bring? Any advice would be helpful, thanks!