I´m using FxCOP and I want to know which are the most important rules or the rules that anybody can´t miss when using this tool.
I´m looking for some article or page with a list of rules that must be used in fxCop, this tool has a lot of rules and it's difficult to select only a few of them.
That would depend very much on what sort of applications and/or APIs you are creating. If you're interested in general-purpose "must" or "should" use lists, you might want to start with the rule sets packaged for Visual Studio Code Analysis (http://msdn.microsoft.com/en-us/library/dd264925.aspx). (N. B.: These include a few extra rules that aren't available in the free version of FxCop.) The following two rule sets might be of particular interest:
(Same answer as on the Microsoft forum.)