Moving to NYC from LA, Tips?

Been a Los Angeles suburbs guy all my life, but my wife got into Albert Einstein College of Medicine and we're moving to the Bronx. Haven't found a job quite yet, but I'd most likely be commuting into manhattan. I'm a bit nervous because of the reputation of the city to "chew me up and spit me out." Any tips for living/working/surviving in New York City? Anything specific about the Bronx I should be aware of?

EDIT: Wow! Thank you guys for being so helpful. Selling my car as I type this, so I'll be back later to check, but keep the wisdom coming!