I just attended a BNA Tax webinar. The webinar was very informative, but as a librarian, one of the most useful pieces of information that I picked up was the link to the BNA Tax Training and Support site. I'm not sure if this accessible to those that do no subscribe to BNA products. Please leave a comment and let me know!
The BNA Training and Support page has a several quick start guides and how to cards, On Demand Learning, which are quick sessions on how to use different parts of BNA Tax, and a Training FAQ towards the bottom.