You say that you do not experience in this field. However, please clarify whether you do not have experience of HR field or you do not have experience of the industry in which you work in.
Anyway, at this stage, you may start with preparation of the Manual of the Job Description (JD) for your company. This will keep yourself busy for few weeks.
Therefore, you may prepare the measures of performance for each department/designation. This is far easier said then done. This will take whole lot of time.
Next thing that you can make is to prepare a career plan for each employee. However, you say that the staff strength has stagnated for the years together at 30. Therefore, I doubt whether your company is growing financially. If the company is growing reasonably then you may go ahead with the career plan for at 50% of the employees.
The next thing that you can do is to talk to the top leadership and tell them to conduct organisational surveys on interpersonal environment, employee satisfaction etc. This will also keep you busy for the next few months.
Hope you are satisfied with the above suggestions.
11th October 2018 From India, Bangalore