Agree with TeacherinFL
I totally agree with TeacherinFL. A good cooperating teacher is critical. If possible, you should find a supportive teacher who wants to work with you.
As far as grade level goes, each grade has its pluses and minuses. Kinder and first grade students are still getting used to going to school. Second grade is pretty easy, because the students are still on the innocent side and the material is pretty simple. In 3rd grade, they start doing mandatory testing for the students. By 4th grade, the students start to get hormonal. They start to grow, and they also grow big "attitudes" to match.
If there are too many teachers in your area, you might want to pick a grade level where there are too few teachers. Usually, there are more than enough elementary teachers to go around. If you pick middle or high school, you will probably be more marketable when you graduate.
Hope this helps.