Buy renters insurance. I cannot stress this enough. It is super cheap, and if you get robbed or your idiot neighbors light their place on fire and it burns down the building, you'll be in better shape than everyone else.

Get a home inspection! This can be any where from 500-1000 bucks but can save you a lot. Check if there is any open permits too! We had two open ones on our garage and we didn't sign until they were closed.

Never accept a counter offer. I assume you've given much thought into the decision to leave your current employer, so don't ignore all of that in favor of a transient benefit.

If you aren't willing to walk away you aren't really negotiating.