I am a second-year Assistant Professor in an engineering department at a US university. I did my Ph.D. in a non-US university and post-docs in the USA. I have a two papers that my Ph.D. students are about to submit, with 5 and 7 authors respectively. A Ph.D. student of mine will be first author in each of those, since he contributed the most, no doubt whatsoever with this.
But what is best for me? I am definitely the person who contributed the most after my student. I had always assumed that I should be the second author. A colleague in Europe told me, however, "Are you crazy? You should be the last author of the list, which is the most prestigious spot after the first author! The main PI or person who helped most the student is always the last author in the list!" So now I am doubting my choice.
Where should my name be on the list, given that I am the main PI and I helped the most? I know it is surely not the main factor for tenure, but I'd like to do this in the most correct way.