provide sufficient staff - overworked staff are less observant.
check references for new staff.
check that qualifications are genuine.
Awareness
make sure your staff are aware of the potential financial consequences of their failing to spot fraud.
Check unusual requests
if an unusual request is received (eg for releasing cargo, or remitting freight) check back with the party authorised to make the request or the alleged originator to make sure it is genuine.
if you are dealing with someone you do not know, make checks and proceed with caution.
Office procedures
establish systems and controls and enforce them.
change employees' job/function from time to time - beware of staff who do not take their holiday entitlement fearing that irregularities in behaviour may be revealed.
institute random checks of files - it may discourage the fraudster from operating.
supervise staff.
Documentation
any important document or communication can, and has been previously, forged, faked or altered. Scrutinise each document carefully for small discrepancies which may reveal that it is a forgery.
check bank signatures (eg. on letters of indemnity) - the high value of cargo, in comparison with the low price of a forged rubber stamp, makes a check with the issuing bank a must when asked to release cargo without original bills of lading.