Protocol for attending a new church?

When I was a kid the only time we went to church was when we were at my grandmother’s house at Christmastime. My grandmother was a very diligent church-goer so we always attended Midnight Mass. I have fond memories of those ceremonies and of the original church we used to attend Midnight Mass at. I’m in college now and I have been wanting to go to a Sunday service at an Episcopal Church for some time now. My family is not from this area and none of my friends are church-goers either, or even Christian, so I would be attending by myself.

My question is this: is there certain etiquette for attending a church you have never attended before? Should I sit in the back? Is there a strict dress-code, or has it become more lax over the years? Do I need to introduce myself to someone? Also, never having been to a Sunday service, what kinds of things should I expect to hear or do at one at an Episcopal Church? Any advice is appreciated.