I have a few key principles that have kept me efficient over the years:

1. Use project management best practices: plan your projects out thoroughly and you'll always have a more productive development cycle.
2. Stick to your development methodology. I like scrum, itarative and agile.
3. Practice before using something new. I always take time to build out a quick proof of concept before I have to apply a new technology to a commercial project I'm working on.
4. Stay current. Trends and approaches are always evolving in the web community. Keeping up to date is essential to maintaining competitiveness.
5. Don't repeat yourself. In coding, writing reusable code will save time later. In project management, keeping everyone up-to-date with good documentation and centralized project management.