Further to what (Cite Contribution) & M. Dinesh Kumar mentioned, also FIRST sit with the MD/Management to understand what THEY actually want to focus on... meaning THEIR priorities. This aspect is of primary importance in such first-time HR department cases [I mean the Organizations... NOT the new HR].
Quite often, the priorities from the HR perspective end up being DIFFERENT from those of the Management. So after spending weeks/months, all you MAY have to hear is, 'I wanted that first' sort of comments.
Make a list of all the work that needs to be done — at a very broad level.
Guess you can make a list & post it in this thread & the members can add to the list. Once you have such a list ready, take time from your boss & ensure you get the focus right. It would be better IF you can make a Minutes-of-Meeting & send it back to him/her so that everyone is on the same page.
The main advantage of such a position that you have is the excellent opportunity to learn in the fast-track mode [you can be sure that not many Freshers ever get such a chance in their careers... most often what you are about to do would come to them after 4-5 years of experience, IF at all].
Coming to the downside, such an exercise has the built-in chance of boomeranging on the Fresher — IF things are not made clear right from the word GO — in BLACK & WHITE. Record EVERY discussion for future reference [quite often, after a couple of years, the primary reason(s) for any decision(s) at the start of the effort get lost, unless they are recorded]. Recording the meetings would also inculcate a sense of professionalism in the way you work... would surely help throughout your career & not just here.
Another reason for recording ALL meetings/interaction is this: though I am sure the Company has valid reasons to appoint a Fresher as the HR Head, it can also mean that they don’t know much about either HR or the business that they are in [150 employees aren’t micro-level for sure]. So when anything goes wrong OR doesn’t go at the speed initially asked for, it’s YOU who will get the stick.
In a nutshell, GRAB the chance but with the associated safeguards into the way you go about the job.
All the Best.
Regards,
TS