Really taking the time to learn your current framework really well. For example, my first rails site was written with a shallow understanding of both rails and ruby, and I ended up writing reams more code than I needed to, and the code I wrote was usually rolling my own when rails/ruby offered a cleaner simpler and more robust way of doing it.

In other words, don't go against the grain of whatever framework/library you are working in. Learn the path of least resistance.