Do Undo Others
That people make mistakes is a fact of life. Practically every non-trivial commercial software product helps protect its users from mistakes by letting them undo their changes. If the user makes a mistake, a keystroke or click of the mouse fixes it. If the user decides that undoing the mistake was itself a mistake, he can reapply the original changes with another keystroke or mouse click.
Not only do undo and redo make the user's job easier, but they also encourage the user to explore the application. If the user can experiment while knowing that any changes are only temporary, he can look around and learn more about the program.
Although undo and redo are standard features in commercial software, they are a bit mysterious to the average Visual Basic developer. This article explains how to implement undo and redo relatively painlessly using XML serializations.