Using MR, MRS, MS, MISS etc when buying tickets
When possible, I try to have the airline issuing the ticket to use ONLY my FIRST and LAST name.
LASTNAME/FIRSTNAME instead of LASTNAME/FIRSTNAME MR
One time when I was flying, my boarding pass printed out as LASTNAME/FIRSTNAMEMR (no spaces) and the immigration officer who was checking my passport against my boarding pass asked me whether the "MR" meant "Mister", or if it was my middle initials!! (my middle initials are is not MR).