First party isolation. Social media buttons and other trackers should not get a global identity for free.
Explicit opt-in to store persistent state at all. An exception should be a cryptographic identity that is only revealed when you click a login button.
No sound without opt-in.
No big data transfers without opt-in. If a site wants to shove 10MB of crap in their article, then they should have to show a page asking permission to use data. And search engines should refuse to index anything behind a bloatwall.