SharePoint Event Troubleshooting Tips

Gary from Combined-Knowledge pointed out this useful post in the WSS SDK today.
http://msdn.microsoft.com/en-us/library/aa979520.aspx
It is a great little list of issues you will come across when working with Event Receivers in SharePoint. You're bound to have come across the one or other weird behaviour when implementing events. You're not alone. The above list mentions a dozen common issues to be careful of.