Three Principles for Helping Your Kids Grow Up Catholic

1. Make Sundays and Holidays special times

Go to Mass and take everyone with you. Make this a habit of weekly life because it is the single most important thing you do to help your children grow up Catholic. If you can't make it every week, don't punish yourself. Go as often as possible for you. But make this a "special time" of household time.
Have special meals. Decorate a little and set the table, cook together, and make this a regular thing. There is nothing that kids remember more than great shared meals.
Visit relatives or friends.
Invite guests into your home for shared meals.
Give gifts to each other. Leave love notes on pillows, or in lunch boxes, and make sure Sundays and holidays are special.

Incorporate symbols and practices of your faith into the "normal stuff" of daily life.

Always pray before meals. For meal prayers, go here.
Spend time in reflective talk with each member of your family or with the family as a whole.
Make Advent and Lent special times. Add elements to the household life that make these seasons "holy times" in your home.
Bring home some Holy Water and use it to bless each other before bedtime, before a big event, or at any other suitable time.
Give each child a personal Bible - but not so fancy they'll never use it! Make this part of their faith formation. As youngsters, give them a child's version of the Bible, and when they're old enough, give them an adult version. For tips on selecting good Bibles, go here.
Gradually add "faith talk" to household life.
Affirm your kids when they do well and are loving.
Assure your kids when they fail or become selfish.

Whatever you do, they will do.
But don't make them uncomfortable by pushing religious practices on them if they aren't familiar with them, or if they don't naturally ask for them.
Take time with them every day if you can.
You are busy: you have a job (maybe two!), a household to run, groceries to buy, garbage to take out, activities to attend for the kids, family responsibilities for older parents or for friends or family who are ill - but in the midst of all this, you will teach your child about life when you keep faith a key element. You will also find yourself feeling happier and more at ease because Grace leads us to be whole and real and loving.