What are some tips for a future 12B (faster promotions, deployments, different types of units, etc.)?

I started my career as a Private (12B), before eventually commissioning..
1) Physical Fitness:
- The military is already a very physically demanding career, but if you want the opportunity to pursue special opportunities such as Airborne, Air Assault, Sapper, Ranger, etc.. you need to show your leadership your grit and that starts with Physical Training.
It's hard to get ahead when you can't keep up.

2) Professional Ethics / Responsibility:
- You are responsible for your actions. Do not let drugs or alcohol determine your career or its opportunities, as these two are the biggest killers I've seen in military careers. If you have impeccable character your leadership will respect you and will go out of their way for you.

3) Know your Engineer Craft:
- As a Junior Enlisted know Weapon Systems, Radios, Land Navigation, and Demolitions. This baseline of knowledge will set you up for initial success and promotions. The best Soldiers I've had were proficient in these areas and were able to help teach others in the unit.

4) Find a Mentor:
- This might be your first Team Leader, Squad Leader, Platoon Sergeant, or Platoon Leader. Regardless, find that person(s) you can go to for advice or guidance. My first mentor was a Master Sergeant, he was the one that recommended and motivated me to pursue a Commission in the first place. I most certainly would not be where I am today without that person.

- Volunteer for schools. Ask for them and prepare for them. You can get a waiver for rank for some of them if you look like you're ready.
- Land navigation and map-reading: get good at it early on.
- Troop Leading Procedures (TLP): Learn what this is and how to use it.
- Ask your fire team leader and squad leader questions and show interest in learning higher-skill level tasks early.
- I'm saying this as a fat, middle-aged software developer, but make fitness a priority. You can't lead if you can't keep up. Rucking was the most important ability in my experience.

Just remember that basic training is exactly that! Knowing and owning your craft comes later. Fixate on all the internal schooling you can grasp. When a slot opens for Ranger School, by all means take it. After that, Sapper School will be a walk in the park, so-to-speak. Between these two schools you can get all you need to know about your job as a 12B. Remember, stay healthy and don't give in to temptation by those who came in to bullshit.