I use the Ctrl keys so frequently that I almost forgot a few good ones. To open a new blank document in Word, press Ctrl n. To open a document, press Ctrl o. Ctrl F4 will close the document, Alt F4 will close the document and the program. If you haven't saved the document, it will prompt you to Save, Don't Save or Cancel. Or you can press Ctrl s before you close it.
Many of these Ctrl key functions will work in other Microsoft programs, but not always. The regular formatting ones such as Ctrl b, Ctrl i, Ctrl s and Ctrl u etc. do work, but some of the others do not work in Outlook, Excel or PowerPoint.
The one we are probably most familiar with is of course Ctrl Alt Delete. I think we all know what that one is for.