I am starting to build up a lot of common methods that will be used across Buisness Objects. e.g. Validating Lookups, Picking out descriptions etc. that will typically need to go out to Database Tables (rather than access internal Buisness Objects)

I have to decide where to put this code....do I just put then all into a common .CS file, Do I create a .DLL separate project... wondering what is the best pracrise here.

Tia.