I have rarely met anyone who can deal with to-do lists that are hundreds of items long - there is a serious mental challenge to scanning something that long without pulling away and finding something less painful to do.
That is where projects come in. In Getting Things Done terms a project is anything which will take more than one action (remembering that an action is something discrete as opposed to a large and sweeping aspiration statement!).
So for me almost everything falls into the category of projects. And inevitabley some projects are more pressing or more important than others. So the actions contained within those projects are ususally the only ones I consider when deciding what to do on any particular day.
A level above that I group projects into discrete sections - usually operational. So either a larger project which contains several elements (a complex website build for example) or an operational area.
What do you do to make sense of your list?