SQL openly runs on port 1433. Using the aforesaid security basics, all ports should be blocked at the server or firewall level to ensure the server is truly safe. If you have an internal server that does not have access to the outside world, port 1433 should be blocked at the hardware firewall level. Because these servers can lie on the DMZ, extra precautions should be taken to limit access and to audit and prepare software to be 'tight'.
With SQL, backup plans, maintenance plans and the individual security roles that can be defined in Microsoft's SQL server should be set and monitored several times throughout the day. Administrators need a strong sa password and should limited the abilities and functionality of users of this database on the database and on the application.
Openly functional ODBC connections under the Administrative Tools applet can leave a client computer ultimately connected to the SQL server. Client computers need to be protected and time out periods should be set on the application. Again ultimately if a workstation is left 'open' or unsecure, a malicious person could access the data by simply using an application such as Microsoft Access to link or import the table into the application by using the ODBC connection that may be setup under this applet.
Systems audits and application audits should be enforced and event logs should be read daily.