Tank,
This depends very much on the task (project) at hand. You could be very unfortunate and find yourself working on an existing legacy system with the occassional change request (CR). Or you could be very fortunate and work on a greenfields project, where everything is new and the whole project is kicked-off with a proper "project brief".
The BABok is a good start.
A good business analyst should be across the following steps: Project initiation, Analysis and Design, Build, Test and Implementation. Depending on the methodology (Waterfall, iterative, agile etc.) used you'll be doing some of these steps. eg. Testing may involve user acceptance testing because if you can write requirements you or someone else should be able to test them. Also, your impact analysis should higlight the implementation and training issues early in the piece.
Anyway, there is a good black and white movie out there called "The Dam Busters" (circa 1954) with Sir Michael Redgrave and Richard Todd. Your local video store might have a copy. Their "project brief" was to blow up the dams that supported some of the German Industry during WWII and thus shorten the war. Not a bad strategy.
Watch it and you'll see each of the above steps, especially keep an eye on the project initiation and analysis&design steps(keep an eye on the dog as well).
Enjoy! This may not be what you expected, but at least you get to watch a movie.
warm regards,
K