After OFAC has determined the base penalty, the following aggravating or mitigating factors may be applied to raise or lower the overall penalty amount.  These factors include:

• willful or reckless violation of law, including factors such as concealment, a pattern of conduct, and management involvement;
• awareness of the conduct at issue;
• harm to sanctions program objectives, including factors such as economic benefit to the sanctioned country and whether the conduct would likely have been eligible for an OFAC license;
• individual characteristics of the company in question, such as commercial sophistication and whether the company has received a penalty notice or a finding of violation from OFAC in the five years preceding the date of the transaction giving rise to the violation;
• the existence, nature and adequacy of a compliance program in place at the time of the violation;
• the remedial response that the company took upon learning of the violation; and
• cooperation with OFAC, through voluntary self-disclosure and/or subsequent cooperation during the investigation.

Generally, in the event of an apparent violation, voluntary self-disclosure should be considered in order to minimize penalties.  For more, see here.