Relationships are critical for teaching.

During my student teaching, I learned that learning can happen when students trust their teacher(s). Students are more likely to ask for help and really engage if they know that their teachers really care about them and are genuine with them.
There are certain age groups I’m just not cut out for.

I have learned by working with this wide age range that I just don’t possess the patience to work with very young kids. I have a lot more patience for older students because they are learning about things that challenge me as a teacher.
Trust your gut and have confidence.

I think that once I find a full-time position (whenever that is), these experiences will stick with me. They will only prepare me and make me a better teacher when I have my own set of students.
Please be nice to your substitute teachers ;)