As far as "what to join" if you do that's upto you and you're temperment and likes, if you want to be ultra safe yet still engaged and doing something neat i would say airforce or navy.
Aircraft Carriers, and Submarines are a good idea if you don't want be up close and personal but each has it's perks and drawbacks..
I'm not speaking from personal experience but from what i've gleamed from family/friends who are in the different services.
I nearly joined the Navy when I was 18 but didn't and looking back in alot of ways I really wish I had.
I'm 33 now with no formal college education just highschool and alot of real world + google know how and experience.
Where as if i'd have joined the Navy i'm 99% sure I would have atleast a bachelors degree + alot of experience in electronics and other things that may of been of great use to me today.
But yah listen to what you're family/friends/others say and take that into count, but it really does boil down to you atleast in my oppinion..
If you're looking and thinking long term where you will be and that seems like a good/logical way to get yourself somewhere go for it.
If not and you are unsure or whatever I would put it off untill you're atleast sure that you've gone thru several options in you're mind of where you want to be at 20/25/30+ etc..
including what you want and how to get there College etc..
If you don't see other good choices I can honestly say seeing friends and my father and other's today.
If you can suck it up and get thru it the military isn't a bad thing but that's me.
The main thing is can you handle it and keep you're sense of who you are, that's the biggest thing that get's driven out of you in bootcamp is you're sense of self and that you are not an individual, but are instead "ONLY" apart of a team/unit which for war/battle is a good thing.
Being a command following drone and having alot of them at you're command and around helping you is a very good thing in battle..
Which on a personal level that can be destructive to self if you're not carefull and aware etc..
Once you get thru it all and used to things and all that i've had 3 step brothers several friends and my father all in various branches of the military and now mostly retired and all glad they did it.
Doesn't mean they don't curse bush often but that's a different thing all together, and one man considered an idiot or not shouldn't be why you do or don't join to me heh.
Anyway, good luck with figuring it all out ;d