Data, data, data: The first thing they teach you (or should teach you, anyway) about optimizing a computer program is measure first, optimize later. Same with personal finance. If you optimize the bits that happen to strike you as being interesting or easy to optimize, you're like the guy who looked for his keys under the lamppost "because that's where the light is." Get something like an app to gather all your financial data and look over it. Where are the biggest advantages to be had? It may be not in the payments you deal with everyday and that come easily to mind (groceries, gas, that sort of thing).