Lets see:

1: don’t get frustrated: games take time to learn, getting frustrated every time they ask what dice to roll or how to do an attack will give you a headache and upset your players, driving them away from the hobby.

2: take frequent breaks. A break every hour or two can help lighten the built up tension of teaching. It gives you and your players a chance to stretch and relax, ask questions etc.

3: always say yes. Even if it’s breaking the rules. Tell them that you’ll allow it even though it goes against the rules.

4: talk to them before the game about what to typically expect at the table. Casual conversations works wonders here. Make sure they understand that this is not a video game, and that there’s not really a wrong way to play the game. Make sure they understand that it’s a cooperative effort between the Dm (you), and each of the players.