The Whoniverse provides two different guides to individual stories.
The Discontinuity Guide
The Discontinuity Guide is a tongue in cheek guide to the continuity of the new series (post-2005), as well as the books, spin-offs, and comic strips. The format is adapted from a book called The Discontinuity Guide by Paul Cornell, Martin Day, and Keith Topping, which covered the classic TV Series, and was republished in 2005. Audio adventures have their own guide on another site, The DiscContinuity Guide.
The Newbies Guide
The Newbies Guide is for those new to Doctor Who. The guides to each story explain what you need to know in order to follow the story, so you can dive right in - even to stories that are part of complicated plot arcs.