11. The plugin should not hijack the admin dashboard.
Users prefer and expect plugins to feel like part of WordPress. Constant nags and overwhelming the admin dashboard with unnecessary alerts detract from this experience.
Upgrade prompts and alerts should be limited in scope and used sparingly or only on the plugin’s setting page. Embedded dashboard widgets must be dismissable. Error messages should include information on how to resolve the issue.
Banner or text link advertising should be excluded from a plugin, including on its settings screen. Advertising on the WordPress Dashboard is historically ineffective, as ideally users rarely visit these screens. Similarly, third party ad systems rarely permit their usage on admin-only screens (notably, Google Ads does not permit its usage there); if they do permit back-end ads, the quality will be low as those systems cannot see the page content to determine good ads. Abusing the guidelines of an advertising system will result in such actions reported to the advertising system.
Developers are welcome and encouraged to include links to their own sites or social networks, as well as locally (within the plugin) including images to enhance that experience.