I soft disagree with folks saying you’re always best finding a group in play. If you’re new to LARP, or even experienced with LARPs but new to big LARP events like Empire, getting dropped into the middle of a massive field of people with no idea what to do can be pretty overwhelming, and if you aren’t confident enough to really push yourself forward and talk to people finding a group can be tough.
A better middle ground between finding a group in-play and getting recruited OC is to reach out to some groups (via here, the Wintermark facebook page, etc.) and get some contacts you can pop and chat to once you hit the field. Then you still get to pick a group that works for you after playing a bit, but you get some crucial direction in-game - oh, that’s X, I spoke to them on facebook and they were happy to talk to my fresh new character, so I’ll go chat to them.
On the other hand if you’re confident or at least willing to talk to strangers in-play, then you’ll be fine just wandering in and seeing what sticks!