Keep in mind that after 2-3 weeks of habitual coffee drinking, your body acclimates to the effects of caffeine and you no longer receive a performance benefit. At that point all drinking coffee does for you is ward off the effects of withdrawal and return you to baseline performance levels - until the effects wear off and withdrawal kicks in again, at which point your performance is below average.
Caffeine is best used strategically, which means not every day. Save it for days where you're feeling particularly low energy, or need a boost to tackle a problem you're not particularly excited about doing.
That said, the half-life of caffeine is around 6 hours, which means if you have a coffee at 3pm, at 3am you still have a quarter-cup's worth of caffeine in your system, preventing you from entering deep sleep. So even then I'd keep caffeine as a first-thing-in-the-morning type of deal.
Naps I'm a big fan of. I take one every day after lunch. The trick is to simply lay down and close your eyes for 20 minutes. Don't worry if you fall asleep or not - just give your eyes a rest. For the first few days/weeks, you might not fall asleep. But eventually your body grows accustomed to the ritual and it becomes easier to actually fall asleep at hat time.