2. Only one person in the family knows where the money goes. Most families have one person who's largely in control of managing the money — and that's fine. The problem occurs when this leads to financial atrophy in the family, where no one but the person holding the checkbook knows where the money goes or is involved in the decision-making process.
If you are not part of the bill-paying, investment decision-making and retirement-savings process, you're at risk if your spouse dies, becomes seriously ill or if you get a divorce. Know the details of your family's finances, spending, investments, debts, savings, etc.
Have monthly meetings about your financial situation so everyone is "in the know." These meetings don't need to be onerous. Sit down with your family to review the balances on all of your accounts, review your rate of savings relative to your income, and discuss if anything needs to be tweaked.
There are numerous benefits to sitting down as a family to review account balances and savings rates together, the most basic of which is that everyone in your family will now be aware of what accounts are out there.