Summarize this article:

Find out if your credit company will allow you to set your payment due date. Many companies will let you select whatever date you wish. Choose a date that you can remember easily. You may also want to choose a date that coincides with your payday, so you will be able to count on having money available. One helpful tip is to set your due date on the same day as your birthday. For example, if your birthday is on April 12th, you could set the 12th of each month as your credit card payment date. Give yourself physical reminders that your payments are due. Write the due date in your calendar. Post it on your cell phone. You can even set an alarm on your phone to alert you when your payment is coming due. You might even want to post notes on your refrigerator, if you are likely to see them there. Anything is a good idea, as long as it works for you. Even more than just using your cell phone calendar, you can use current Internet sites as reminders. Websites like MemotoMe.com or RemembertheMilk.com can be scheduled to give you a monthly reminder a few days before your payment is due.  MemotoMe.com lets you create a private account, protected with a password and linked to your email. You will receive notices when your dates are coming due. RemembertheMilk.com links to your email as well as other social media interfaces. Give yourself enough advance notice to write and send the payment.
Set your payment due date. Make reminders for yourself. Use current technology to help remember.