How do I know which GST/BAS return basis to use? 

Invoice based GST relies on the GST component from both invoices and cash transactions.

Invoice basis and accruals basis.
Accruals Basis is also known as non-payments based GST returns.  Payments based GST is calculating GST on actual money that you have received.

The GST component on invoice basis is calculated based on the difference between opening and closing debtors and the difference between opening and closing creditors as well as any cash transactions entered via the transaction entry screen.

A business will choose to use invoice based GST because either they have to by law or they want to pay or receive their GST as soon as possible. If your profits are over a certain amount you are obliged by law to be on invoice based GST.

Payments and cash based GST includes the GST component for transactions entered solely in the transaction entry screen. Invoices do not affect the GST return on payments or cash based GST. Furthermore, prior GST periods do not impact on a current GST return when the return is payments or cash based. Adjustments also have no bearing on a GST return when it is payments based.