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.