Good Friday is the only day of the year in which there is no Mass. On the day of the ultimate sacrifice, we don't recreate that sacrifice in our liturgy. Instead, the service for Good Friday (which used to be called MOPS--Mass of the Pre-Sanctified) is divided into three parts. As Richard John Neuhaus wrote in Death on a Friday Afternoon, things in this story happen in threes.
I adore the first reading--Isaiah's Suffering Servant. I wrote out the entire first reading here. I was born on Good Friday, so maybe that's why I'm so attached to this reading, and this liturgy as a whole.
The veneration of the cross is my favorite part. If you've never seen it done, essentially the priest takes a crucifix (or a cross, depending on what the church has) and the people come up to kiss, bow, prostrate themselves before it, or otherwise honor the cross. It's a BIG cross--don't think any sort of wall-sized crucifixes here. Ours is about five or six feet and it's beautiful. Everyone can come up and individually venerate the cross as he or she wants. Watching the kids do it--kiss Jesus' pierced feet, or his knees, which are right about at eye level with them--is always a touching part of this. During this the choir sings the reproaches and some hymnody. All music is unaccompanied today. The church itself is very stark: no altar cloths, no candles, no statues on the altar. It's all removed.
At St. Pat's, we do the tre ore--the three hour reflection on the Seven Last Words of Jesus. It's three hours (not continuous) of meditations on Jesus' death, and what His last words to us were. The priests take turns giving the meditations, because they're also hearing confessions from noon to 2:45.
I'm very solemn on Good Friday. I come home and watch The Passion of the Christ, and I have a small dinner, but generally I don't do anything other than read, pray, and attend service.