There is no point in treating the Guidance Counselling Service as if it were some sort of educational secret service. We need to ensure that everybody knows we exist and what we do. To that end I created a poster and this accompanies this lesson as an attachment below. It has a section for each guidance counsellor to enter details of how to make appointments.
Print as many copies of this as you need and, ideally, laminate these before placing them on all school notice-boards. If your school has a waiting room or area for visitors, put one there also. The idea is to let all students, teachers, parents and visitors know what the guidance counselling service offers.
There are, of course, other things that help publicise the service. When you run an event such as a careers evening, make sure everybody knows about it. Use all social media at your disposal. After the event, be slow to remove event posters as the after-event publicity is important too.
Never, ever assume that people know what you do or what you offer. At least once a year avail of a few minutes at a staff meeting or parents' gathering to tell them what you do. Have a presentation ready (Powerpoint or Keynote) for such occasions.