Okay, I'm just going to come out and say it. Worksets are to Revit what Layers are to AutoCAD. Oh, that hurts! But I should add that Layering in AutoCAD has ballooned way beyond what is needed or was intended for. Worksets, on the other hand, seem to be shrinking. More and more is controlled behind the scenes. I've done projects where I didn't even activate Worksets. When working on large scale projects, with a team, worksets will be your best friend. One out of two experts agree that it's a good idea to turn them on right from the get go. It's a bit of a pain to add things to them after the fact. It would be comparable in AutoCAD to drawing everything and trying to make Layers after. Again, ouch! Here are some basic rules for worksets:
Make them general; Envelope, Core, Partitions, Fixtures etc.
You probably will only need 10 or so.
Make a spreadsheet before you start. This will map how the Revit elements will be organized onto Worksets.