(bit late to the party, sorry... been rather preocupado, although according to Dave Cox, I'm not allowed to complain unless I'm endeavoring to walk to Argentina, which I'm not, so I'll get on with it.)
Dear New Teacher:
Are you sure about this? I mean, I feel it's only fair to warn you. Older people in your life, parents, etc, have probably filled your head with silly notions about how teaching is a good job. It's rapidly becoming not that great a job.
Pension-wise, New York just went to Tier Six. SIX. I won't go into details, but Tier Six is pretty shitty. Granted, ten years from now, they will probably be on Tier Eight, and you will be feeling all smug to be on Tier Six. Tier Eight is going to be, like, a standard-issue leather jacket and spiky shoulder pads and lessons on shooting an automatic weapon out the back of a moving pickup truck.
Otherwise intelligent, nice people will assume you had to go into teaching because you are such a dimwit, you can't do anything else, or perhaps just misguided about what is important in life, namely having expensive stuff. You will hear some variation on the "If you are so smart, why are you a teacher?" question at least once every few months. From people it would be impolitic to offend with a smartass response, like your boyfriend's dad. Have an answer ready for that, one that is both diplomatic and speaks your truth.
You probably suspect the children will love you. They will not love you. Once you get decent at this, they will grudgingly respect you. That will take at least three years.
You will pour your every ounce of intellect and ability into teaching the Algebra 2 class of your life, and then the outside testing agency paid to test your kids and rate you based on their performance will write a lazy, error-ridden, confusingly-worded exam that only reflects about 75% of the standards they told you to teach. Some kids you really like, who you know learned a whole bunch in your class, will fail it. You will beat yourself up for the rest of the summer.
Your first year will be 50% drudgery, 45% heartache, and 5% awesomeness. After seven years I've gotten that down to about 40:40:20.
Okay, if you're still sure, understanding all that... you probably have a chance. And, given all that, this is the best job in the world. Getting someone else to understand something is HARD. But it's an intellectual puzzle that's worth building a career on.
I'm rooting for you.
But maybe open a 401k.
Update 30 Jun: Okay, to counteract the negativity above (even though all of it is totally true, and newbs need to hear it), here is a
List of Things That Are Awesome about Teaching that Politicians Probably Can't Screw Up:
1. You get to hang out with young people all day. Who are funny, idealistic, emotional, open-minded, and overall, a trip.
2. You get to learn all the new slang before other adults.
3. Office supplies.
4. You can propagandize for your favorite mathematicians TEAM LEIBNIZ!
5. You have the power to make a place where people have to spend 45 minutes a day into a joyful place of learning and safe risk-taking.
6. You get to play a part in what kind of people kids will turn into, hence what kind of world we live in.
7. Continuing to learn new things is a job requirement.
8. You will get to work with colleagues who are some of the kindest, smartest, most genuine people you have ever met.
9. That moment you find the key to that part of a person's brain that unlocks the thing you want her to understand.
10. That moment a class asks its own question and runs with it.
In a nutshell: you get to share the best of civilization with new humans. That will be enough to sustain you through a whole lot.