Upload & Sell: Off
ASMP and APA are both active in Los Angeles. Go to their meetings, meet other assistants and photographers, and let them you're interested in assisting.
Commercial and editorial is a people business. Meet the people, get the business.
Or if retail portraiture is more your thing, PPA is also active there. Same advice applies.
Whatever your poison, the trade groups are a fantastic resource that everyone should avail themselves of. When you find the right one, become a dues-paying member, too. They're fighting you every day locally and in Washington, and it takes money to do that.