10. Failure in not having a Will (or not updating your existing Will)
9. Failure to have successor Executors, successor Guardians and successor Trustees
8. Failure of not planning or discussing your Will with your beneficiaries
7. Failure to take taxes into consideration when preparing your Will
6. Failure to have a Power of Attorney
5. Failure to have an Advance Directive for Medical Care with appointment for a health care agent ("living will")
4. Appointing the wrong fiduciaries
3. Failure to plan for contingent beneficiaries
2. Failure to review and update the beneficiaries of the life insurance policies (and/or retirement plans)
1. Two Words: Internet Will