Dan's 10 essential technology skills and practices contains some good tips (although I must admit I'm not good with keyboard shortcuts – I think more graphically and tend to use the mouse).
I have a couple more to add.
When creating Word documents don't use the "enter" key to create spaces between paragraphs. The right way is to use the paragraph settings to set the "before and after" spacing. Otherwise, you can't make efficient use of things like paragraph numbering or bullets. And by using the "before and after" setting, you can often easily adjust the length of a document a bit to make it fit on one less page.
And don't use page breaks to keep headings and paragaphs, or multiple paragraphs together. The "keep with next" feature within the paragraph settings does a far better job, and continues to work when things get moved around during editing. That's assuming, of course, that you have used the "before and after" setting to create paragraph spacing.
And if you want to keep a consistent look and formatting among your headings and paragraphs, use "styles".
One thing I like about Office 2007 is that the controls used to do these various things are very visible and easy to find. I highly recomend the upgrade.
Two thumbs up for styles in Word. Not only do they help with a consistent, easy-to-change look and feel, but they also make building indexes and tables of contents a snap. This is indispensable in law school summaries and similar large documents.