Going to the memorial? You've made an excellent choice. It is endearing that you wish to make a good first impression.
There is no need to be nervous. You have probably thought that Jehovah's Witnesses are stuffy people, but they are far from it. They are humble and down to Earth and have a great sense of humor. Just relax and be yourself-- your real self because Jehovah's Witnesses are uncomfortable around hypocrites.
Everybody tries to be polite and pass the plate of crackers and the glass of wine along to the new fellow, so make sure to be polite in return and sample their wares. Don't forget to tell them how delicious it is. You might also want to take a c.d. of kingdom melodies and lead the dance under the full moon in the KH parking lot before you leave. This will much please them and they will be sure to invite you back next year.