Mobile First Web Development best practices include designing with a mobile mindset, optimizing images and media for faster load times, implementing touch-friendly controls and gestures, utilizing progressive enhancement techniques, and conducting thorough testing on multiple devices and screen sizes.

Challenges in Mobile First Development include dealing with limited screen real estate, integrating third-party software and plugins, optimizing images and media for different screen sizes, and ensuring cross-browser compatibility. Developers also need to consider responsive typography, font sizes, and the performance impact of various design elements.

There are various tools and technologies available for Mobile First Web Development. Popular frameworks like Bootstrap and Foundation offer pre-built responsive components and grids. CSS media queries allow developers to apply specific styles based on the device's screen size. Testing tools such as BrowserStack and Device Mode within browser developer tools help ensure a consistent experience across devices.