Before you get too far into development, decide which core QuickBooks Online features you want your app to use.
Make sure you implement and pre-create entities so your app can reference them in transactions.
For example, transactions in QuickBooks frequently need to reference common entities such as account, taxcode, or customer.
If you have pre-created versions of common objects and entities, all your app needs to do is reference their IDs while creating a transaction, such as an invoice or bill.
If these entities don’t already exist, the transactions your app creates won’t have anything to reference. Referenced entities can’t be created on the fly within a transaction.