The DevTV videos are one of the best ways for new Revit programmers to start to get their head around things, and they have been updated for Revit 2015. Links:

  • DevTV Introduction to Revit 2015 Programming Part 1 – a short video tutorial demonstrating the basic steps to start developing with the Revit .NET API – View online | Download
  • DevTV Introduction to Revit 2015 Programming Part 2 – a short video tutorial demonstrating selection and filtering API through a Room Renumbering application – View online | Download
  • Revit 2015 API Labs

The Building Coder: On Handling Warnings and Failures

If you head over to this link, you will find a nice collection of Revit API resources, including:

  • My First Revit Plug-in (self-paced tutorial guide for a smooth introduction into the programming world)
  • SDK downloads
  • Introduction to Revit 2011/2012 Programming (DevTV videos)

There is also a very handy package from the Revit API Labs.  If you unzip the following file, you can find actual class handout documents, presentation slides, and source code samples for both VB and CS (C Sharp, C#) languages:
Revit API 2012 Training (zip – 12726Kb)
Autodesk – Developer Center – Autodesk� Revit� Architecture, Autodesk� Revit� Structure and Autodesk� Revit� MEP