If you feel like you want to physically push yourself, submit to absolute authority, become an a member of a cohesive team, and become an efficient killing machine, I say go for it.
One thing about Marines -- I've never met a man that wasn't proud to be one, and as they are fond of saying, "There is no such thing as a 'former' Marine! Once a Marine, always a Marine! Semper Fi!"
Talen, the best thing you can do is just get some running time in before you go. Running is about 60% of the PT you'll have in Boot. Also, it will help immencely in forced marches.
All this if you did decide on my beloved Corps. If you did, you'll either love it or hate it. There is no in between. As far as the hair, I went in with a full skull full, but others shave before hand. Your choise. If you do go, think really hard about what your going to do after you get out.
Use that to get what ever MOS you'll get. Don't be a grunt if you want to be an office manager. And don't be an admin geek if you want to get out and be a cop or something. Plan for the future as such.
On Marine Recon. What ever MOS you get, if your serious on getting into Recon; jump for every chance to go to various schools. Some of those schools would be;
Jump school
Ranger school
any survival school you can get but Navy's SEAR school is the best
Rigger school (repel master and such)
Doesn't hurt to be a really fucking good shot either.
Study your knowledge (slang for pertnet info on tactics and such)