I think the biggest mistake people do is not understanding that surgery is like sculpture. With sculpture you get one thing or the other.
You get this OR that.
The "I'm gonna fix this and get this and this"-attitude drives me insane because it doesn't care that doing this will affect the appearance of other areas.
The viewing of mouth, eyes etc as separate parts feels like a childs perspective that might work for makeup but not for sculpture.
I feel this approach can come from the person who wants surgery done (fine then) but what's worse from the plastic surgeons who are selling their services targeted to specific body parts.
I'm not sure people in general look upon themselves and others as three-dimensional. I've noticed many apply makeup looking straight in the mirror without ever checking profile view.
Even among art students I feel people generally are better at drawing and painting, which is about creating an illusion, but find sculpture more difficult even though it shouldn't be hard to make a 3D-version of a 3D-object if you REALLY understand what you see.
I think this goes to show that the three-dimensional formate is very very unforgiving and hard for most to understand.
I think people who consider surgery should keep in mind that they:
1) Are three-dimensional and can be seen from any angle -and there are many.
2) Can be seen in motion when the skin and muscles look different than when kept still.
3) Are constantly changing and could be in for major future unknown changes due to genetics, lifestyle, weight fluctuation etc.
4) Are made of meat and skin which are pretty crappy materials to sculpt with for long lasting pieces. Even bones suck compared to a foundation made of let's say steel.
5) Might not be as aware of the human proportions and the mystery of beauty (solve that one please) as they believe they are and the surgeons might not be either (can they even draw a human likeness?)
The above is aimed at anyone who is thinking of surgery but I'm not saying everyone would benefit from reading it, I'm sure there are plenty who doesn't need lecturing. Since I've talked to a few who craves surgery I do feel that some however, do need a reality check. Sorry