Tom Sydney Kerckhove is writing a series of articles, explaining how he uses GTD with Taskwarrior. The first five articles are up:
Part1 - Intro
Part2 - Collection
Part3 - Tickling
Part4 - Processing
Part5 - Doing
The articles are well-written, and the material logically presented. We recommend you read them, and check for the latest articles.
This post will be updated as more articles are published.