In essence auditing means checking the accounting data to ensure it’s accurate, meets all relevant standards and regulations. When you think about it, isn’t it something you also could do yourself?

Yes, there’s the compulsory audit, but regardless if you fall into the category of someone who has to have one or not, you can and should audit yourself. By no means should it be to the same extent as the auditor would come and look at your accounting, but in some areas it will probably go into more detail. 

Those “some areas” are those where you either have or can see that most mistakes happen or are prone to happen. Identify those accounts, processes and devise a plan to have them audited.

The “auditing procedures” your planning should be regular and detailed enough to really help you in finding possible mistakes or errors made. Regular in the sense that you should keep the discipline in doing them so as they would be effective – either once a month, once a week or if need be, more often. Level of detail is hugely subject to the area and the mistakes you audit for so what I would suggest in general here, is to keep it as effective and this at both sides – so that the control would help to discover something, but then again so it’s not more time consuming as needed.