I have posted about the Autodesk BIM Curriculum before, but it is worth mentioning again. It is a great collection of resources, videos, whitepapers, downloadables, and targeted lessons that can help improve your understanding and ability when it comes to specific BIM tasks.
For example, there is a focused set of lessons relating to quantity takeoff in Revit and Navisworks.
Some of these videos have also been uploaded to Youtube. Here is a playlist:
Main lesson page:
Lesson 3: Model-Based Estimating and Quantity Takeoff | BIM Curriculum