Use Outlook’s categorization system.

Use Outlook’s categorization system.
These tips apply primarily to Windows 7
Source: PC World
 

Outlook lets you color-code messages, task-list items, calendar 

entries, and even contacts into as many as six categories. 

Figure out a system and stick to it: red for business, for 

example, and blue for personal items. Or color-code items by 

level of urgency: green for “must do today,” blue for “to do 

this week,” and yellow for “to do this month.”