5 Things I Will/Wont Do in My Business Again

Here is something productive for the forum, and hopefully there is some good input from us all. I'm looking for 5 things you wont ever do again, like a lessons learned, either with your business or clients, or both. And then 5 things you've done right, planned or not, that have helped it out and you'll do again or continue doing.

5 Things I won't do again:

1. Tell a customer a fixed scheduled time. Say they call up, need X done, I say sure, I'll be there at 1100 tomorrow...