Hi Renu,
I can give you one simple idea.
Firstly take a note on existing HR policies - attendance, recruitment, employee engagement, performance management, etc.
Do that first for your knowledge purpose. Being an HR in the firm, you should anyways know them right.
Secondly study the graphs, study your people. How many of them are on time, how many people take many leaves, who have been the employee of the month, who has been performing consistently, etc.
Sitting idle and asking your supervisor for tasks is not at all helping you because -
You would not learn
If you plan to switch, you would be taken back to recpetionist.
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HR is more of proactive activities. Honestly, if you put up there's nothing much HR does. I myself sit idle many times. But in those time, I increase my knowledge, help people out, study my firm, study my people and because of my these idle times, i've been able to proactively suggest my employer few ideas.
I had been the only HR with no one to guide. I had to perform on my own. No one knew what to do including me. Had been through your situation. It's perfect, relax.
Just suggest ideas to your HR Manager on how to improve performance of your people or something like that...
Always remember, in today's time Proactive people are appreciated and valued, rather than people who'd wait for someone to give them something to work on.
Prove your worth, your knowledge by you deciding what is right for you. At the max, you'd be claimed wrong, they'd disapprove your suggestion, you'd fall, but eventually you'd rise. You'd know how things work. Theory is much different and easier than practical life scenarios....
Wish you luck & All the best. :)