First and foremost, front-end developer should have the fundamental knowledge and skills in HTML – to be able to structure web pages; in CSS – to make web pages look as intended on the design; in JavaScript – to program web pages functionality. Second, building websites includes a bunch of repetitive tasks. This is where front-end frameworks and libraries come into use. They have a lot of ready made code that developers can reuse so this helps developers to make the job done faster. Among other tech skills which are also important for a front-end developer are: сross-browser and device testing, web performance optimization (WPO) and search engine optimization (SEO).
Finding people who are strong programmers is just a part of the task. A truly good web developer should also have an understanding of web design principles, adequate communication skills as well as eagerness to learn new stuff.