[brianogilvie]

I group by context not only for planning, as I mentioned earlier, but also because I tend to select all the contexts that are currently available (in my office, for instance, I'll select not only Office but also Phone, Reflection, Reading, Computer, and Agenda contexts for people who are in the office that day). The context groupings then help me determine the specific context for a given action. I like a little redundancy.

As for deciding what to do: I have an Urgent perspective that groups and sorts remaining actions by due date; a Flagged perspective that shows me all available actions with flags; a Tickler perspective that shows me actions that start today, tomorrow, and in the next week; and a basic Do perspective with available actions grouped by context. I'll review Urgent, Flagged, and Tickler first thing in the morning, decide what's top priority for the day, get those things done, then go back to those perspectives. If I decide that I've made sufficient progress on the things in those perspectives, then I'll move on to my basic Do perspective; if that looks too big, I'll change the action filter from available to next.

For me, flags are not necessarily for a given day's work; instead, I use them to mark important tasks (those that seem more important than others in a time frame of a couple weeks to a few months). Something with a flag and an approaching due date is both urgent and important; something with an approaching due date is urgent but not important; something with a flag but no due date is important but not urgent; and something with neither is...well, you get the idea.

During my reviews, I review flags and due dates, and I use start dates to push things forward. That way my decisions about importance and urgency are reviewed more or less weekly (depending on the project/action list's review frequency).

Note: all of this represents an ideal--I'm not always as systematic as I should be. The one thing that saves my bacon is frequent reviews. Reviews are useful because they ensure that open commitments get regular attention. But I find that they also help me become more mindful of those commitments even when I don't have my OmniFocus list in front of me.