Another key to budgeting is to regularly check how you're doing. A family that has a lot going on can easily lose track of certain expenses or not realize that certain bills are adding up more than they used to. After your first month of trying to stick to a budget, sit down again and see how the family did.
Don't be too hard on yourself if you fail to live up to your budget goals at first. You might need to re-evaluate your budget if you made it unrealistically strict, or you might not have realized how much you were spending in a particular category. Self discipline doesn't come quickly, after all. Every budget will require tinkering, and you can't expect things to be easy or perfect the first time you try. The important thing is to not get discouraged. On the other hand, if you did very well, that might be a sign that you can further tighten your budget to save even more.
Once you do get used to your budget, don't assume you'll always stick to it. Check again every month or so to make sure. And remember to account for new and seasonal expenses, like higher energy bills in the hot summer months, or the costs of Christmas gifts in December.