As you are already working in Admin, you might be aware of the basic roles in Admin like staff facilities,attendance rules, stationery procurement & issues,Transport,Canteen,Uniforms,identity cards, Liasoning,Record maintenance, House keeping etc. And when you have opted to be the Head of Admin in another concern/organization it shall be a Supervisory post for the total area, handling a team,coordinating with rest HODs,delivering on time,ensuring smooth flow of operations.
Simply you need to be leading the team, building rapport with the colleagues and rest HODs,delivering your roles.
But you need to be aggressive with your team on one side and get the results. Aggressive (as you might be aware) does not mean being harsh but getting the things done in a desired fashion.
All the best in your new assignment.
From India, Hyderabad