Easter is a good serivce to visit a church for the first time. There are lots of people that only go on Easter and Christmas, so you don't stand out. Most churches I've been to are fine with dress slacks or khaki's a nice shirt (tie completely optional). They give you a bulletin at the door with the schedule of events, and some indicate when to stand. You can take communion or set it out, no problem.
Around here, communion is held regularly at churches weekly or monthly or quarterly, depending on the denomination. "Holy week" usually has a special Thursday service that will include some historic meal or footwashing or something. Friday commemorates the actual crucifiction. Then Sunday a.m. there is often a very early service to remember Mary going the tomb. Then the normal service with scads of kids all dressed up wanting the easter egg hunt to start!
As far as the etiquette for taking the communion: most protestant religions would say that if you recognize that Christ died for you, then you may partake. (some care whether or not you've been baptized, etc, but no one will tackle you at the cup to see if you qualify.)
For you rookies, there are several ways to take communion. Just do what everyone around you does. Sometimes it gets passed around witness style. Sometimes one big cup, sometimes a bunch of little plastic cups. Sometimes little wafers, sometimes a whole loaf of regular leavened bread. We usually break off a piece of the bread, dip in in the grape juice (Welch's) and pop it in your mouth. AND No lightning bolts through the stained glass directly into my heart that first time! Then at our church you can stop up at the front of the church at the prayer rail and kneel and pray silently for a few minutes.
Sorry this is so long, I just thought some one might wonder what the procedure is....my 2 cents. Nancy