Making a test order will let you check if your store is ready to go. You will have to go through the same steps as your customers.
Go to your store website, add some product into the shopping basket and click buy.
If you want to test online Payments at this point, you can create a test payment method. Go to Settings > Payments > Add > Custom payment method and name it i.e Test payment.
After placing the order go back to the dashboard and check if it appears in Orders tab.