Remove the core. You can cut around it with a paring knife But it's easier to strike the core firmly with the "butt" of your palm. You can usually pull or twist it out after that strike, tearing off the last few connections.
Wash it in cold water, drain it well, core hole down.
If you want large intact leaves for wrapping Vietnamese or Chinese style dishes, then run the cold water directly into the hole where the core was. The lettuce will start to fill with water. The weight of the water will start separating the leaves from each other so you can easily pull them away.
Iceberg is often cut in generous wedges, drizzled with a good bleu cheese style dressing and served upright.
It shows up in some asian soups, but I've never been impressed with this usage. There's no flavor and the textural aspect doesn't appeal to me. The chinese love a variety of texture so that's probably why they use it this way.
They'll also use iceberg lettuce to line the clay/sand pot before filling with other ingredients and braising. This imparts a subtle vegetal impact, simplifies clean up and is an interesting presentation.
Chinese lettuce wraps are probably my favorite way to eat iceberg lettuce. You get the crunch of the lettuce and it adds a lot of moisture in the eating of it. RasaMalayasia has a pretty good recipe but there are many variations. The dried mushroom is pretty traditional. Jeff Smith uses half pork, half chicken which I think plays well. And I like a lot finely chopped ginger as well when I cook the meat. RasaMalaysia uses no ginger.