What is the best way to request a new duty station?

Point to consider, the duty station you are requesting must have a need for your MOS. Not all locations are available to all MOS's. Locally, check with the Retention NCO. They have access to a program that lists vacancies by MOS (through Strength Management) throughout the army. They then use this information to "lock in" an assignment for a reenlistment contract. Branch Managers use the same system when considering reassignment requests or to fill TO&E manpower requests sent up by the unit.

Call them. I had never called my branch in 17 years of service when my father died, mother was alone, I wanted to be close to her. When I ask for an assignment in Florida he laughed at me. At that point I was straight up with him and little forceful in a nice way, I told him that I have never called and asked for anything of assignment branch before, always excepted branche assignments with no complaints, I needed this assignment. He then found me an assignment, curtailed my 3 year tour in Germany by 6 months with tour completed. Assigned me to MEPS as a Security Interviewer. Caveat being that after I reached my 20 year mark I put in for retirement, which was NO PROBLEM!

Made a deal with the devil!

Some branch managers would rather have your retention NCO/career counselor or first line give them a call or email. Some others don't really care. I will suggest you speak to your career counselor first. Better still, find out what your branch managers preference is before calling directly. You get a faster response when you call directly.

https://fmsweb.army.mil/unprotected/splash/

Use this site as a weapon - it gives you a break down of MTOE and exactly what rank and skill level is in that unit. This is more up to date than ACT.

I would email him/her first and then go from there. I've found that to be the easiest way, if your window is open you should talk to retention first.

Start with unit retention.

Being on good terms with the ones who cut the orders helps or even the ones who request the orders. Make yourself as versatile as possible. Keep your ear to the ground for people in your MOS who are either getting out or changing stations. If there's going to be an opening in an area you want to go, you might be able to get ahead of the game.

Personally, I would talk to them in person. Emailing is impersonal and he might get a hundred emails a day, so he might not even read it right away. Calling isn't any better unless you have a close working relationship because then he might get off the phone and wonder who was calling him. I personally worked with the Marine who requested orders, so I knew personnel changes ahead of time and since he knew my work ethic as well as who I was, it'd made it easier if I wanted to expand my experience going to a different unit.

call

Call

In all honesty it depend on the branch manager. I have heard some horror stories about some of them when you call personally. I personally have never experienced that. I would start with an email stating what your hopes are and wait for a response. If it's extremely important then give them a call. I have an awesome branch manager NCO and civilian and have had no issues with communicating with either.