Accessibility isn't a feature, it's a baseline. Here's the practical checklist I use on every project to ensure websites work for everyone, regardless of ability or device.
Semantic HTML First
Use proper heading hierarchy (h1 through h6), landmark elements (nav, main, footer, aside), and meaningful HTML elements (button for buttons, a for links). Screen readers navigate by structure. If your structure is wrong, your site is broken for assistive technology.
Color and Contrast
WCAG 2.1 requires a minimum contrast ratio of 4.5:1 for normal text and 3:1 for large text. Test with a contrast checker. Don't rely on color alone to convey information, use icons, labels, and patterns as secondary indicators.
Keyboard Navigation
Every interactive element must be reachable via keyboard. Focus states must be visible. Tab order should follow the visual layout. Test by unplugging your mouse and navigating your entire site with Tab, Enter, Space, and Escape.