steveo, I agree with your insights.

While I was attending college I made money charging for tuning. I worked on some interesting projects and met some great people. But I also learned it's important to have the right expectations before going into a project.

Customer has some version of "Everything is new so can you start tuning right away?" Take the time to check basics... fuel pressure, charging voltage, battery condition, do filters appear new, etc. Just as it doesn't make sense to build a house on a crumbling foundation, it doesn't make sense to tune around bad components.

Accept that you may be taking steps backward. Folks will tell you what they want but don't be surprised if they decide they don't want it once they have it. It's still billable time.

The simplest changes often create unwanted side effects to deal with later. This is especially true if you change a variable that you are unfamiliar with.

Most folks don't understand or recognize the difference between a perfect tune and one that is good enough. Spending time improving the tune over multiple iterations after achieving "good enough" is a good way to lose time and $$.

What seemed to work best for me was charging for tuning time, rather than setting a cost for the tune. In some cases folks would work in stages as they had $$. Everyone does it differently though.