Order Of Execution
This is more of a warning than a tip. If you have a field with both an onChange event defined and an onBlur event defined, then you shouldn't make any assumptions about the order the different events will occur. For example, in Internet Explorer 6, the onChange event happens before the onBlur event. The same is true for Netscape 4 and Opera 5. However, in the Notes/Domino 6 client and in Netscape 6, the onBlur event happens before the onChange event.
The "tip" to take to heart here is not to make any assumptions about the order of execution, unless you are controlling the order of execution. And make sure to test your code in as many environments as possible. The order of executions listed above were checked in the Windows 2000 client - Macintosh may be different. And other browsers not listed were not tested.