Mac Maintenance

Here's Apple's recommended maintenance:
Mac Maintenance Quick Assist

1. Keep Things Up to Date
   Make it a point to check for Apple software updates once a month
   No problem, I have it set to check automatically
2. Put Your Files Away
   Put your files away where you can easily find them.
   A question about email attachments: should I just keep the email and attachment, or save the attachment and delete the email?
   My habit has been to do both: if I sure I want the attachment, I will save it to a sensible location.
   The problem comes with attachments that I can't use immediately, but don't want to throw away either. I have at least 150 M of such stuff.