There is very little that has to be done to enable the audit trail capability. Once in the Features record of the field definition, select 'Support Audit Trail' and change it to 'Yes'. 

Then, when you republish, any change that you make to a record in that type will add to a log, stored in a drilldown called 'Audit Trail'. The log will describe precisely what changed in the record, along with a record of who changed it and when it was changed. 

Figure 62: Showing the audit trail list available at the bottom of the record display. 

Figure 63: Showing the configuration of the audit trail 

Note also that the audit trail cannot be edited by the user in any way, providing a secure record of the changes.