I'm presently working with my 5th student teacher. I truly enjoy the experience, and enjoy the energy & ideas a new teacher brings to the table. If you are going to work with a student teacher in your classroom, there are some things that you need to consider.
First, you need to want to have a student teacher!!! I've heard sad stories of student teachers who were placed with cooperating teachers that did not want them. This is so sad to me & I truly have no idea why a teacher would take a student teacher if they did not want them?!?! You can say no!
Second, you need to know the expectations of the university that you are working with. Each one is different. I've worked with 3 universities in the Nashville Metro area. One only once...because I learned after the fact that they really didn't want my opinion on their program!(they were truly doing a disservice to their teachers by not preparing them...and not holding them to higher standards!! I wanted to fail the student teacher & they told me no. She later got "let go" from three different school districts.) Some universities offer orientation for new cooperating teachers, and I highly recommend you attend. Also, most have a guide book that will provide you with all the information you need. If there is something you don't understand, ask their advisor. They are usually very greatful that you have opened your room & life up to their students, and more than willing to help you out in any way you need!
Third, share the good, bad, and ugly with your student teacher. They need to hear it all, because at some point they will be dealing with all that you have dealt(well, they might not get their classroom picked up and dropped on a car by a tornado like I did my first year of teaching). They need to hear what you've struggled with, where you have found success, and how you deal with the day to day.
Forth, be prepared!!!! I have a book for my student teachers to look through when they first visit me. I has my background information, my classroom mission statement, my expectations, images of student art work, classroom procedures, standards, and curriculum. This will provide a strong beginning to your student teacher's time with you. They will have a good sense of what you do in your classroom & what they can expect from their time with you.
Fifth, always be honest & encouraging. Sometimes they do not seem like they can go hand in hand....but trust me...they can! They need to hear from you, and you're not helping them by sugar coating everything. I keep a daily log book(just a notebook). In it..I write the day, class, and comments I have for the lesson. Sometimes I write more than others. This gives them direct feedback to what they are doing & specific situations. The university advisers seem to like this as well. They look through it when they come to do their observations, and it allows them to see how things are progressing.
Finally....ENJOY IT!!!!!!!!!!!!!!! I can't tell you how much fun I've had over the years working with student teachers. Yes, it is a lot of work...but so worth it! Investing into others is what we do as teachers, and becoming a cooperating teacher allows you to experience this at a different level.