Congratulations, I spent 5 years in and loved every minute of it. I enlisted in nov of 1994 and have never regreted the time I spent on Active Duty one minute. I only got out because I wanted to make more money in the private sector. Now some 5 years later I am. I picked up Sergeant a little over 3 years... shoot for that and your money. Ask to go on every meritorious board there is, every Marine of the Quarter thing Marine of the Year...you name it ask to be on the board. Put your time in studying and reviewing even after boot camp. I was meritoriously promoted through my ranks and it will bring your the respect of your piers and subordinates. OK, enough ranting, on to my advice for you:
First bit of advice.... dont' go to boot camp with a tattoo of a Bull Dog or the Word Marine anywhere on you, they'll find it and you will pay on the quarter deck, oh will you pay. Those who where Guides or Squad Leaders (me), know that we paid each and everyday almost. My platoon, 3070 Lima Company, when we got to Camp P. my Senior wanted to be the first to the pit, so he marched us right there after getting off the bus, no putting s*** away, just straight to the pit and worked us for like 30 minutes. Anyway, it was an honor to be the hardass platoon in boot camp.
Secondly, don't have your family send you any food in boot camp. Oh yeah, if you get a good pic of your girl, share it with the others....(hahaha). Your D.I.'s will feed to you how they will steal old Mary Jane Rotten Crotch from you, it's funny.
Third, never complain, just do the job and deal with it. Everything that is going to be done to you has been done to thousands of others, you are not the first, nor will you ever be the last.
Fourth, It is a honor for a Marine Corps Drill Instructor to train you in the image he things a Marine Should be. Never think that they don't care, that they hate you, they are training you to be someone they could trust next to them in a fighting hole, or in a hallway in Falujah fighting the enemy.
Fifth, never regreat the decision you have made, NEVER! Don't listen to people who say you've made a bad mistake. I was 20 when I joined and it was the best decision I made. I used my G.I. Bill when I got out and right now it's something like $1000 a month while your in school full-time.
Ok, enough of me rambling on, Semper Fidelis to all my fellow Marines. You have to earn the Title MARINE. Honor, Courage, Commitment.