Make sure that you know lots of interesting stories that relate to the actual story of Pesach and the Yetziya.
Have nice little Divrei Torah scattered about.
Let the kids say what they learnt in school, and delve into it to show that you really care about what they’re saying.
If they’re the type who like these discussions, don’t try to rush them on…
IMHO, that’s how a great Seder works.
Pesach’s the best! 🙂