Let's say you want to keep a card on file in the event that your items aren't returned or are damaged.
You can attach a Credit Card Authorization form to your Terms & Conditions to ensure it is included in quotes for your clients to download, fill out, and return to you. Learn more here.
Once you receive this form from your clients, you can add this to the client's contact file (article) or to the 'Files' tab of the project (article). You can then manually capture a payment from the 'Billing' tab of the project. Learn more here.