Yes talking of mistakes, not doing your research would also be another... unfortunately what tends to happen only to often is people arrive on the forum when itβs too late ! Look at the recent spate of poor results being posted as a example of this.
Yes we can guide them to a better option for future, but a lot of the time the mistake has cost them their valuable donor area and/or caused scarring. Or the typical multi grafts in the hairline.
So many mistakes can be avoided by taking time to research the best option which gives you the best chance of a good result. Nothing is guaranteed but you can certainly drastically reduce the known risks to having a hair transplant.