Here's Bill's advice that we use on a REGULAR basis!
"When I announced I was going into business, my dad told me I should know the secret of the "clamp" trick.
When he was a young machine designer he worked under an engineer who was extremely hard to please. Dad was determined to do his best and please this guy -- even taking work home until he thought it was right. On one project they were working on a machine that had converyor belt on it. The engineer reviewed my dad's blueprint and said, "Are you done, Bill?" Dad said he was, so the engineer said, "Well I think you need to put a clamp over here." My dad, utterly frustrated said, "I've been over and over these plans and I assure you we don't need a clamp there."
The engineer said, "I know that and you know that, but this customer we're working with here is anal as hell and he'll find something wrong no matter what. So we'll put this clamp over here in a place that's easy to spot and easy to erase. Then he'll spot the flaw, suggest a correction and get his jollies.
To Dad's amazement the customer scanned the plans until he spotted the unnecessary clamp and his eyes lit up. He asked Dad if he was done. Dad said he was. Then he said, "Well I think you did an admirable job here, young man, but do you think we really need a clamp over here." Dad looked at the engineer and the engineer said, "You know, I don't think we need a clamp there, and we could probably save a bunch, considering how many machines we're making. Let's take that clamp out.
The customer puffed out his chest and said, "Very well then, proceed with the plan minus the clamp." Before the customer made his way out the building, Dad received a wink from the engineer, grabbed the eraser, and low and behold that clamp was gone.
We use the clamp trick from time to time, and you'll need to too. When we get an anal customer like that, Jane will look at me and I'll look at her and will both say at the same time, "CLAMP TRICK!" This is usually leaving a phone number out of the design or maybe even misspelling a word on a sketch if a big enough clamp is needed.
Good luck, though, I do think this is one of the greatest businesses. Not the greatest money, but the satisfaction you'll have from doing a job-well-done, you can't put a price on."