Well, I think the most important thing to remember is that most "traditions" we learn in our parishes about how to conduct ourselves in the church (such as how to enter a church, where to stand/sit, etc) are specific to the parish and not absolute laws. That's something that was hard for me as a convert when I branched out and went to other parishes, realizing that many things that I had learned as absolutes were really just my parish. The best thing to do is just look at what other people in the parish you are visiting are doing, and do likewise.
Being from the Seattle area just like you, and having been to both your parish and the one you are talking about now, I can give you some more specific advice though. At Assumption, when you are in the gated area just outside the doors to the church, people cross themselves three times before entering the narthex, then upon entering the narthex, they venerate the icons in the narthex. Then, you go find your pew by walking along the SIDE aisles (not down the center). They normally cross themselves before entering the pew. Also, they sit a lot. When they leave the church, some people cross themselves three times, some just leave.