Google translate

This is the most versatile of the language translation resources available on the internet. While it is not always perfect, it is generally accurate and can be relied upon to tell you how to say whatever you want in German. It not only shows you what to say, but it allows you to speak your sentences in a wide choice of languages and then play back the German translation. It therefore is a good resource not only for becoming more familiar with German sentence structure, but above all, with vocabulary and pronunciation.

Leo

A huge database of German vocabulary entries, which can be accessed from this page, with the option of going from several languages to German.

Deutsche Welle

This is by far the most comprehensive and versatile set of online instructional materials available on the internet. They include numerous videos illustrating various situations and often following an interesting story line. There are many exercises to check your comprehension and allow you to practice your pronunciation. And best of all, they are all free!

Goethe Institutes

The Goethe Institutes are the premiere face-to-face language schools, located throughout Germany and in many other countries. For deep and lasting immersion, they are by far the best choice for learning German efficiently and accurately, and if you attend one in a German-speaking country, you can live in an environment where you will hear the language all around you. Thus this is the best choice for a total immersion experience.