Moved to California on my own for college. Moved to Mammoth on my own (had friends visiting all the time, so not quite the same). Moved to Colorado on my own after getting a job offer there.
Most recently moved to Switzerland alone cause I figured why the fuck not. I'm here till October and it's wonderful.
I suggest doing it as often as possible. You really learn how to meet people and handle yourself. I was incredibly shy and still am on occasion, but my experiences have opened me up so much. The moment you tell a stranger what you are doing, they are interested in your story. It becomes so easy to make friends.
If you're going for Orange County, Huntington Beach is a great place to up and move to. It's pretty young and there is a ton to do. It's also really easy to make friends there. I've met plenty of people just out walking around down there. If you are going to go Newport, I'd go balboa. It is it's own little bubble of awesome. Laguna Beach is cool, but kinda separate from everything. If you're into that scene but looking to go a tad cheaper, Hermosa/Manhattan Beach are excellent and Long Beach has a totally different feel.
I'd go huntington beach and look for a posting on craigslist with a house of people your age near the beach. There are a lot of them. Get a job on Main Street near the beach and you're set. The US Surf open is probably one of my favorite weeks of the year in CA. And surprising fact, the US Surf Open is also the largest free concert series in the US. I've seen Jimmy Eat World, Alkaline Trio, The Sounds, Weezer and MGMT all at the Surf Open. There are tons of other bands, but those are the ones I cared to see.