[whpalmer4]

Bring up the flagged/overdue view (which you already have, right?), and work on everything there, which by virtue of being overdue or imminently due or flagged is your collection of stuff you need to get done immediately, if not sooner. I agree with the "use due dates sparingly" crowd, though I'm of the opinion that you can be more liberal with them so long as you get them done — the harm comes, in my opinion, when you have due dates in your current work that you regularly ignore.

Once you've got those fires put out for the day, bring up your next action view of all of your projects and work on whatever seems appropriate.

One of the vital features of OmniFocus which can help you make good choices there is the Review feature, which allows you to make sure you are regularly looking at each of your projects. When you bring up a project view grouped by next review, OmniFocus shows you your projects in order of when they were last marked reviewed (command-shift-R, or add the Mark Reviewed button to your toolbar). When a project is marked reviewed, the next review date is updated by the project review interval for that project, so you can have projects that get seen every day, or every 3 days, or every year, you pick (I think the default value is a week). During the review, you make sure the project reflects the current reality, add or change actions as needed, maybe flag or unflag actions or the entire project, etc. and generally make sure it is proceeding as desired. A nice workflow for making sure all of your projects keep moving along is to force yourself to do one (or more) action from each project as you review it, though this will work best if you keep your actions reasonably sized. You adjust the review interval for the project in the inspector. Once you've marked a project reviewed, it is moved in the view to the appropriate group and the next project to be reviewed is selected. If you do some reviewing every day, and review all the projects whose next review date is today (or earlier), then you shouldn't have any projects falling through the cracks because OmniFocus will help you systematically monitor all of your work.