The best advice I can give you is to treat them as you wish to be treated; with kindness and respect. Understand that you are an adult and you cannot expect a child to act like an adult. Even the best behaved kids act up sometimes. "You can't put an adults head on a child's body" my grandmother used to say.

Hopefully you'll fall in love with them and enjoy your time with them.

It sounds like you're going into the relationship with your eyes wide open, which is good because spouses come and go, but you're kids are yours for life.