What you're looking for is to test order placement!
Unit tests
There are a bunch of ways to do this, but what you probably need / want is to create unit tests. The two most prevalent at this time are:
- PHPUnit (https://github.com/EcomDev/EcomDev_PHPUnit)
- PHPSpec (https://github.com/MageTest/MageSpec)
Fortunately for you there's a new site for screencasts that just popped up and it goes through unit testing in general, and specifically for Magento:
Manual
Now, to answer your question. You shouldn't have to use your real credit card for development/testing if you're using a gateway with a test mode or a sandbox. Make sure your payment gateway provides this - change the API credentials to this sandbox environment and use test credit card data (see: http://www.getcreditcardnumbers.com/). All of the major providers offer this service.
Next - HOW do you test this? The old-fashioned way to do this is just bite the bullet and manually enter the order. (See: https://magento.stackexchange.com/a/836/336) This will allow you to enter the order over and over to test and debug.
