OK, you might already know this one, but if not, it can be handy to filter emails by sorting on more than one column.  Say you not only want to find those emails sent by a particular person, but also to group those that have attachments.  Click on the From column heading to sort ascending (you can also click on the column heading again to reverse the sort direction).  Then hold shift, and click on the attachment column (paperclip icon) to add it to the sort.  You’re now grouping those emails that have attachments and that are sent by the same person, which should make it easier to find that elusive email.

As a bonus (reminder) tip, remember that when you’re viewing an email folder, typing a letter or two will highlight an email based on the field by which you’re currently sorting your emails.  The same also works when viewing Contacts, where Outlook will highlight the first entry that matches what you type.