The important principle to remember is to separate responsibilities so one person does not have all the responsibility in check writing or bill paying. A few ideas include:
A person writes checks while another person records the transaction in the accounting records.
The person who writes the checks does not sign the checks. Instead, another person signs the check, or, even better, two different people sign off on the check.
A person (not the person who writes the check) reviews bank activity regularly to monitor for any suspicious activity.