If you work in a large software-oriented company, your code may be frequently subject to rigorous code reviews. Furthermore, you're likely to be surrounded by other developers. Some who may know more about development than you do. Working just a few seats away from these individuals can be highly motivating, as it creates pressure for you to have ideas that are worthy to contribute.
In contrast, if you're a freelance web developer or work in a small startup, you may be the only person around who knows much about web development (or IT in general). In this situation, you may be expected to be the expert, and it may be hard to find anyone to mentor you or critique your work. While such an environment can help motivate you to build your expertise and self-reliance, there is a risk that you'll miss some opportunities to reach your full potential.
To excel, it's necessary to be proactive in challenging yourself and keeping up with ever-evolving best practices. Seek out others who can critique your code. Consider attending or starting groups of developers. Never be comfortable about your level of expertise; keep reading forums and articles about the latest technologies, techniques, security issues, conventions, and design patterns. It can also pay to search or post in forums to get answers not just about how to solve a particular problem, but whether a particular solution is the best way.
Another technique to get a sense of where web development is headed is to occasionally look at the technologies listed in job postings for web developers. Even if you're not looking for a job, this can help you see what technologies others are using.
Continue learning... Maybe even take a class or earn a certification.