If you’re using credit cards and not tracking them with a rewards spreadsheet, you’re missing out on hundreds—maybe thousands—of dollars in free travel, cashback, and premium perks. Most cards reward you more in specific spending categories, but if you're swiping blindly, you’re leaving free money on the table. A simple spreadsheet (yes, really) can help you match the right card to the right purchase, automate smarter spending, and unlock serious rewards.