I think it is awesome that you want to serve and this is a great time in the military. (it always is :)) My advice is to not lock yourself on the idea of a service. See what they all have to offer. They all have very similar benefits as far as being a vet. goes. Training in the service is great as well.
If you want to get in the Military now after HS the best thing to do is go ROTC with a focus on Nursing. And this is where shopping the service choice will benefit you. Who will pay for your school, ie scholarship, full ride or partial. Budget is tight and they don't guarantee active duty anymore, its competitive now. Which school will give you the best benefits too. Not all schools are created equal whether its the RN program the ROTC program or the extra benefits they give to ROTC students.
My advice is to pick the schools you want to go to then find out who their ROTC recruiter is. Call them and see what they can do for you. They will be able to tell you the benefits, the likelihood you will be able to get a scholarship if into the school at all. You need to be accepted into the school before you can go ROTC.
They will only entertain the idea of you as a possible recruit if you show self motivation and drive. If you can, go to their office and sit with them, they like that.
When you finish the 4 year program you will commission as an 0-1 in whatever service you sign up with as an RN for at least a 4 year obligation. (If i were to do it again I would probably go Air Force). I can give you more specifics on the Army if you'd like.
If you want to enlist, the Army has a great LPN program and options later to go RN (tough and really good programs). But I still suggest you go for your RN via ROTC as the pay is way better and the life is easier as an Officer.
Military life in general is not for everyone. There is a commitment to an external idea verse the self and some people have a hard time with it. ROTC gives you a taste and you can decide if its for you. You need to be willing to get into good physical fitness. If you're fat and you go to a recruiter you automatically fall down low on their priority. Not to say its not possible to get into shape and still be able to get in. There is a standard and you must meet it. If you decide its for you, the physical part is easy and will come with hard work.
Please ask questions. Military commitment is just that. A commitment. Not an easy choice, but the gains and benefits you receive as a person and worth it if its for you.