Many of the times looking at a working code will cut through the confusion and get us straight to the thing we want to implement or the feature we are adding to our wp8 app.
Below is a chart of top 30 samples that walk through Windows Phone 8 features and technologies.
Windows Phone Samples Chart
Learn through code : http://aka.ms/wp8samples
Nokia Code Samples : http://developer.nokia.com/resources/code-samples
Developer Code samples
Happy coding !