There isn't really a best way to do this. In general, however, class modules are good to use when you have code that you're going to reuse in numerous places. Of course, so are procedures.
If you're going to reuse code in different projects, it makes sense to put the code in a class and expose its functionality through methods and properties. If your reused code is limited to the single project, you might want to use classes if you want to reserve the option of making the code reusable through multiple projects. If not, just use procedures.
As an example, I have a dbUtils class that sets up some connection strings, does some standard formatting, handles updates, deletes, and inserts, and so on. I have used it in several different projects.
HTH
Bob