What should I do to prepare to get promoted to SGT?

God damn, you are destined for greatness!

You always want to be working towards two ranks ahead. That means once you make SPC you should be working toward points for SSG. Once you’re a SGT you should be stacking your NCOER and ERB for SFC.

Right now, the best investment you can make is the long term investments you’ll need to out compete your 91B peers for E5 and E6. That long term investment is college. You can be finished with your AA or BA while you’re competing for E6, while your peers are struggling to get enough points. Also, start working on those correspondence courses slowly but steady so you aren’t trying to cram for points.
Once you pin SPC you should be enrolled in DLC1, complete that immediately. Do that well because your grade is factored into your future GPA at NCO schools. That means if you just BS through it, you won’t be able to make Commandants List in the future, which is worth extra promotion points.

Finally, pick up any class you can. Any extra duties you can.

You start by taking on MORE responsibilities, proving to your Command that you deserve those stripes. Being a Sergeant is not about just wearing the rank. It's about Leadership, both in missions and people. It's about responsibilities. It's about taking care of your Soldiers. It's about coming in to work before everyone else and leaving after everyone else. It's about mentorship. It's about always learning. It's about being an NCO.

If your Leadership has given you less responsibilities, that should tell you that they feel you aren't ready yet. So...your first step is to prove to your Command that you are ready. You will need to do that by taking on extra responsibilities. Taking on Soldiers. Learning new things. Read the Creed of the Noncommissioned Officer. When you read it, if it doesn't give you chills and the desire to be an NCO and not just a Sergeant.....then you are not ready.

I think the PFC is referring to her having less on her plate as a Jr soldier, not that she has been non trusted with it.

The are two aspects to getting E5. Sorry folks, I think in terms of the rules of the game. Promotion Points as mentioned by the SPC, and leadership and responsibility as mentioned by the Sr NCO's here.

Administratively those translate into Strong APFT, Weapons, Civilian Education, Mil Education, and awards. The "leadership" aspect the NCO's are referring to is check the box process in the form of your Commander allowing your promotion packet to go up. Which realistically, I'm hoping your CO isn't blindly signing them all, and ideally the 1SG vets them and recommends UP/DOWN to the commander.

Looking at the promotion point calculator tells you what you should focus on, and getting your NCO's to think of you as their go to soldier greases the wheels for getting the Commander to sign your promotion packet.