Strategy 1: Try looking at the major job websites: Indeed (I've been recruited twice from just having my resume posted), Allhealthcarejobs, Monster, etc. Use a variety of search terms: psych nurse, psychiatric nurse, mental health nurse, behavioral health nurse
Strategy 2: Join the APNA (Home - American Psychiatric Nurses Association
). They have a job listing board...it's also an opportunity to network
Strategy 3: Find where the psych hospitals are in the US (Google is your friend for this), get to their websites, and look for openings and/or contact them directly.
As far as moving to Cali...if you're a new grad, bad idea: we're over-saturated with new grads, especially southern CA and all along the coast (inland CA may offer hope). New grad residencies are few and very tough to get into (even fewer for psych), and the other jobs want experience. BSNs are strongly preferred...but to be honest, new grad BSNs can't even get into nursing homes/LTC, so everyone's struggling.
Not saying you can't try to get a job in Cali because you never know, but it's very hard. If you have some experience (1-2 years, at least!) your chances are better. So if you don't already have experience, try to get that experience elsewhere first.