When I first signed up for the Citi Platinum Dividend Card, I had intended to pay off the balance twice a month. I have actually only been paying it off once a month but I use Quicken to help keep me on top of what I've spent so I can always pay off the balance in full after my second paycheck of the month.
Every month after paying off the last Citi balance, I create a new Quicken transaction and date it a day or so after my 2nd paycheck will be deposited (this is well before my payment due date). I set this up as a transfer between my checking account and my Citi account.
In the check number field (also used for DEP, ATM, and EFT) I place the word HOLD which is my own designation for something that will happen in the future, but still needs action (like to enter an actual payment online for example). I think of these transactions as money "set aside" for the future, but by entering them in this way they are highly visible in Quicken and I see the immediate impace to my balances.
Then I constantly update that balance to always match what has been charged to the Citi card up until the day I pay the statement balance (on or just after paycheck #2). I use the "update" feature in Quicken to download all credit card transactions often. When I am home during the week, I even do this daily...but I do it at least once a week. Once the credit card transactions are downloaded, I note the total due on the card, and update the HOLD transaction to match making the result of that future payment a zero balance.
The net effect of this is that every time we use the card, the impact is noted in our checking account almost immediately. This allows me to always stay on top of the balance and I have been able to pay my credit card balances in full since earlier this year.
Other quicken tips: How to add I-Bonds to Quicken and using a personal receivables account to track future incoming money.