Library InfoHelp desk. The library staff can check your references (usually you can have your reference list done and ready for checking a few days before the due date) and give you advice and training on how to correct the list.
Before you come to the library or if you can't get in a good place to go to check referencing styles is the Referencing LibGuide. There are many referencing styles like APA, Vancouver, Harvard and your lecturer will often specify one specific style in the Subject Outline and marking rubric. To see how some styles look compared to each other, check out the Parts of Citation from the Referencing LibGuide.
There are also plenty of useful explanations scattered across the other LibGuides. My favourites are: