As Google keeps changing SEO regulations, what can websites do to get higher ranks without getting penalties?

SEO has never changed contrary to popular belief. Google has always said that make the content for the user not search engines, use unique and high quality content and get links from high quality relevent resources across the web. Make the site navigable and content easy to find, don't use too much advertisement, etc.This core values haven't changed at all, but what has changes are the tricks people use to game the system. When said get links, we tried to game the system by getting links from everywhere - so google gave us penguin. We tried to use copied content and used article farms to game the system - so google gave us panda. We used too much advertisement to generate more money - so google gave us Top Heavy, and so on. And as Google is trying to evolve more to try to be one step ahead of these spammers, they needed a new platform to quickly integrate next generation changes - so you've got the Humming bird. But still the core fundamental requirements to rank remains the same