What can I do to earn a Promotion from SPC to CPL?

Both are E-4 so it's not really a "promotion" over the other. It's a delineation of duties (kinda like MSG vs 1SG). CPL is an NCO thus a leadership position. SPC is not. Couple of factors will come into play:

1) is there a need for a junior leader? If your mTOE or TDA does not support a CPL, likely you will not be made into one.

2) have you demonstrated leadership skills necessary to be able to do the job.

To be a cpl, you need to be in a leadership slot, like Assistance Squad leader. Just take on more responsibly and you make cpl. Then that when the real fun begins. Good luck and I hope this help you out.

PFC Tuan Trang the only CPL that I've seen here, Meade, was because she had so much accomplished as a SPC and her CDR wanted to have everything on a NCOER. But that's CDR discretion. You could get to a Company as a CPL and the CDR can say, I don't need you as a CPL, you are gonna be SPC again. Which is not a demotion since you are in the same pay grade. CPT (Join to see) correct me if I'm wrong.

Set your sights higher than Corporal. Get in college, do correspondence courses, get your "sexy" badges (airborne, air assault, sapper) go to WLC and learn learn learn. You want to set yourself up for success to be a Sergeant. Corporal is what will be given to you if your are filling or higher needs you to fill a sergeants position.

You have to get promoted to SPC first, do your TIG requirement as a SPC, do your SSD-1 and submit a E-5 promotion board packet, get boarded and there has to be a NCO position in your unit in order to get laterally promoted to CPL.

Go tell your squad leader you want a team leader position. The rank will come. Don't worry about volunteering. Being a Team Leader will keep you busy in your personal time.

My question to you, is what are you doing to get to the next level? Are you trying to get promoted just because of money or are you genuinely an outstanding Soldier who goes far and beyond your peers? You should be focused on how to be a leader. As far as volunteering if that is what you want to do and its genuine then do it, but dont just do something for the next rank.
You should be focusing on leading from the front, going beyond the normal daily duties, doing military education and when eligible sign up for civilian courses. You are our future NCO and you must lead from the front.

PFC,
To become a CPL you need to get a lateral promotion or become DA select.

If you get a lateral, most of the time when you leave the unit that gave you the lateral will lateral you back to SPC before you PCS. I left as a CPL and my new BN CMD decided to keep me as a CPL but know the option is there.

The way you are DA selected is your unit sends up a packet recommending you to be DA selected. In which case your extra services I'm sure couldn't hurt. Becoming DA select is rare.

You need to be serving in an E5 position in order to get a lateral that is done with a 4187 signed by your BN CMD.

PFC Tuan Trang I applaud your internal drive and desire to get promoted. Being laterally appointed to Corporal is in my humble opinion something that your actions will determine. Lead, Lead, Lead. Live the Creed of the Noncommissioned Officer and always put the needs of the Army, The Organization, and your Soldiers before your own. Doing community service is great, but do it for the service to the community, not some advancement for yourself. You may get awarded the Military Outstanding Volunteer Serice Medal but make no mistake, the lateral appointment is not an award. It is recognition of your ability to lead and take care of Soldiers.... NOT YOURSELF! If you are doing it right, you will be working ten times harder as a Corporal than as a specialist. You will be working for your Soldiers and their Family Members, the Unit and the Army. In addition to all the extra work, you will more than likely be the NCOIC of all the details that the Sergeants don't want... I made many Soldiers and great young leaders wear that rank who had demonstrated outstanding ability to lead their peers. Anybody can make Sergeant...It takes someone very special to wear the rank of Corporal!

You have to be laterally appointed by your Company Commander. You have to be in an E5 slot, performing duties as an NCO. Once that is done, your company will not see the E5...until you leave or forever. Generally once the Command does that they will not get the right manning backfill. Hence why seeing CPLs is rare. Not to say the Command may do it anyway. They usually pick someone who is a seasoned soldier and has potential to lead, and is right on the verge of E5 anyway