Never accept a counter-offer
I've taken 3 counter offers at the same company. Will probably do it again if my current job search goes well. In a company like mine you can't just ask for a raise and expect to get it. However, if a key resource resigns wheels start turning. All the sudden they can give significant increases. Otherwise you grind it out year after year hoping for 3% but some people get nothing. I'm going to hate my life no matter the job. So I will work for the highest bidder or most leave time.