I've been attending Mass with children for 13 years now. I'm not saying I'm an expert. In fact, I've learned most of these lessons the most embarrassing way possible. So I share them with you.
12) Sing at Mass. It'll inspire your kids to sing. And there's few things in this world better for people to hear in Church than the sound of children singing.
11) When entering the pew, separate the problem children. You know which ones they are.
10) Sit near families with badly behaved children. The spectacle of the children will keep your children quiet because they'll be in shock and wondering why they can't get away with that. And your children will look great in comparison.
9) Don't believe the old people who tell you after Mass that your kids are soooo well behaved. Old people often grade children on a curve. I'm not saying anything against it. We all deserve a little curve, especially children. But on the other hand, don't listen to the people who get annoyed at your children at Mass either and make it seem like your family is a bother to everyone else. You belong there. And so do your children. When people start thinking that other people are a distraction from their faith, that's the real problem.
8) Don't let your kids go to the bathroom during Mass. There's something about bathrooms and kids. Letting one child go to the bathroom not only makes all your other children instantly come down with irritable bowel syndrome, it also makes every other kid they pass on their way to the bathroom have to follow. Here's the thing, I looked it up, there's never been a headline "Kid explodes during Mass, parishioners soaked in urine." Never saw it. Not once. (Well there was one but it was The World News and it was the infamous wolf boy so...) In short, don't let them go to the bathroom.
7) Sometimes let them go to the bathroom. I know what I said. But it's a judgment call.
6) Tell your kids that the sign of peace isn't like the line after the little league game where you have to high five everyone and tell them "good game."
5) Dress up your kids real nice and make a lot of noise packing your kids into the van to go to Mass on Sunday morning. It's good for your neighbors to see where you're going. It takes away all their excuses not to go. I know what Jesus said about praying in private and not bringing attention to yourself but you never know who you might inspire to go to Mass. I know you don't feel like an inspiration after getting a bunch of kids ready but sometimes inspiration just happens when you're just doing your best. Let them see ya'.
4) Be careful taking little ones up with your for Communion. If you're not paying attention they might just get an early sacrament. I myself received an early First Communion in the first grade from a distracted Jesuit. And my mother punished me!!! The Jesuit got off scot-free, of course. Figures, right?
3) Prepare your children for certain Masses. Tell them palm is not a weapon. Explain that they don't need to emote quite so much when they yell "Crucify Him." We're not method Catholics. Oh, and prepare them for all the begats at the Christmas vigil. There's something about saying the word "begat" when we go over the genealogy of Jesus that makes kids giggle. Don't know why. It just does. Studies have been done and it's been proved that every single kid in the world (even the aforementioned wolf boy) will at least crack a smile anytime they hear someone struggling to say, "And Solomon begat Roboam. And Roboam begat Abia. And Abia begat Asa. And Asa begat Josaphat. And Josaphat begat Joram. And Joram begat Ozias." Don't know why it makes them giggle. It just does.
2) Let each kid put a dollar or two in the collection basket. Makes them feel generous. Sometimes feeling generous actually inspires generosity. Not all the time. But sometimes.
1) The little kids who can't read want to hold the missal and the ones who can read, don't want to. Just try to limit the volume on the page flipping. Oh, and don't tell them it's called a missal until about college age. You say "missal" they hear "missile." They get funny ideas.
Bonus reason and maybe the most important one. As a parent, all you can do is point your child in the right direction. When you bring your children to Mass you're pointing them in the right direction. If you teach them to focus on the Blessed Sacrament during Mass, it makes it easier for the Blessed Sacrament to become the focus of their life.