A relaxed environment where making mistakes is encouraged as that's the only way they'll learn. Involvement is key!! Children aren't going to learn sat in silence just listening to a tutor, so getting involved allows us to work through questions and topics together which helps retain the content so much more.
After struggling with maths in younger years of secondary school I had someone closer to my age help me, because I felt more comfortable with her cause she wasn't a teacher or older I learnt and retained so much more and didn't feel judged when making mistakes. This overall made me enjoy the subject rather than just doing it cause I have to. This is why the environment is key to any lesson if a student isn't comfortable then they will be more focused on that feeling rather than learning.