What does it mean to be a 13F, is it a good choice. Is Ranger school a possibility?

As a Forward Observer I was in combat, calling for fire and putting rounds down range everyday during the fighting season. If you want to avoid combat we have no use for you. If you want combat the opportunity is there but no promises.

Become a expert in your field, and your options are limitless. I loved being FIST. Only downside we get loaned out, never really have a home.

Yes it's a good choice you will see combat and you can go ranger

Whatever you do avoid echelons higher than battalion. Divisons and Brigades are where fisters' careers and morale dies! We thrive to be in the suck but in Division we act like a 13D and just coffee. Not to mention constantly have to listen to O4s and above run their mouths. Every combat MOS I see here hates their life and if you look hard enough, you can see it in their eyes. To be fair, there are some very important skills you can learn as a senior NCO in Divison but when you are lower enlisted, you should be on the hill not in the office. Just my 2 cents

Pretty much Special Forces.

Unless something as changed recently, there is no MOS restriction on volunteering for Ranger School. Practically, the class size is usually somewhere around 290 students, 200 will be from the Infantry Basic Leadership Course (2LT's), E-3/E-4's from the Ranger Battalions, and the various other Officer BLC and ALC courses, and those slots assigned to other Military organizations, including Foreign ones. That means everyone else gets what's left and getting it as a 13F E-2 won't be easy. If you are really interested in the Rangers, I would talk to the recruiter about Option 40, which is a contract to get the chance to go to the Ranger Regiment. I've on only seen it on an 11B Infantry contract, but there are other MOS's in the Regiment.
Just to be clear, on Option 40 gets you a try for the Regiment, not the School. Enlisted Rangers go through Ranger Assessment and Selection Program, which I believe is also 8 weeks long. The Enlisted Rangers are then sent to the regular Ranger School somewhere around E-3/E4.