Clip on. If my dress doesn't have anywhere to clip, I clip to my laptop bag entering and leaving the building and just carry it if I leave my desk. We are supposed to wear it at all times- we can't get in to another part of a building without it.
Most employees do not wear it with a lanyard. Guests are required to wear a lanyard.
I wear mine on a lanyard. Ours have these bulky plastic cases that the actual badge slides into and they're too heavy for any of the pretty, necklace type holders (tried it and broke one) and I feel like they pull your shirts weird if you clip them on since they're so heavy and you have to have them displayed above your waist so I just stick with a lanyard.