Your financial tips for living as a “traditional family”?

As a couple, we would like to have many children and that the mother can stay with the little ones until they start kindergarten at the age of 3. Of course, this means a career break for the mother. In the long term, we would like to buy and renovate a functional house, not something fancy. We want to take a long-term approach so that we never have money problems and can make ends meet in old age. Are there any general tips you can share with us for this classic life plan?