Use Mr, Ms, Doctor or Professor, after the first mention we refer to people by their surname, unless they are: a Knight a Dame or a peer, in which they everytime their name is mention would to refer to them with their title: e.g. Dame Shirley Bassey
If the title has been abbreviated, you must use a full stop.
Job titles should be written with capital letters when an actual person is being spoken about, for example:
Doctor Mews will see you now.
‘Can you take my temperature, Doctor?’
I’ve always wanted to become a doctor.
In politics titles should never be used as personal titles:
The Minster for Education, Ed Balls
Minster for Education Balls, or Minster Ed Balls
If the person has an MBE, CBE or OBE this must be referred to at the first mention of their name, after that you can refer by their surname.