#1: Smile - This may seem simple - but it's important. Smile at new families (and regular families). Parents are already nervous about the noise that their children create during the service. Your smile reassures them that they are their children are welcome.
#2: Prepare - Do you have a safe change table in an accessible place? Has it been cleaned recently? Do you have a place for a family to feed their children or deal with a fussy baby? Just as you're not likely to stay at a restaurant without a place to sit - neither is a family likely to stay at a church that never intends for children to be present.
#3: Be Open - Even if you have a nice clean change table - families may offer suggestions that you had never thought about before. Perhaps a rocking chair in the Narthex for nursing mothers. Maybe bags of toys in the sanctuary. Be open to these suggestions.
#4: Help - A struggling mom would be glad for an extra set of hands to help care for her two wiggly children during the sermon. And that dad with a baby in his arms would love to sing the hymns if only he could open the book. Don't be afraid to lend a hand. It may be more appreciated than you know.
#5: Pray - Pray for families - in the prayers at church as well as in your personal prayers. And tell families that you are praying for them. In many ways, this is perhaps the single most important thing that you can do. Hold the struggles and triumphs of your congregation's families in your prayers.