Be sure to run a live test transaction before launching your initial online component:  Donate Now/Orders page, Online Auction, or Ticket Sales.   Testing one element is sufficient to ensure your credit card settings will work for all three venues.    Vaulting requires additional permissions  and a different test which you can do in lieu of the test described below (or as a separate test later).

To test the Donate Now/orders page or Ticket Sales, simply logout and complete a transaction as a visitor to your site will, donating $1 and paying by credit card.

If your Online Auction will be the first source of online payments:

1. Add an Item to your catalog:  Test Item, type = sellable, cost = $1 and make it available in your online auction.
2. Sign in to create an account as visitors to your site will, buy the test item, then pay by credit card.

If you have set-up your credit card processing before you are ready to launch any of the above components, you can also run a quick test by Generating an Internal Order  (use your own User record, and Add Item "Cash Donation during ticket sale" which is embedded on your site.

If the credit card transaction is successful - you're good to go.