If you're looking to understand (and/or jack up) your morning kick, there are four things to know about your cup of Joe.
Beans Matter, But Not A Ton
Arabica, which is the standard species of coffee plant, and far more prized as a source of quality coffee, typically has about ~.5% caffeine content. Among different arabica varietals, though, there are slight minor variations based on origin. Robusta beans, however, generally feature ~2.4% caffeine. That said, robusta beans are generally known as tasting tar-like on the whole, which accounts for their use in lower-quality/cost supermarket coffees.
Roasting Differences Help a Bit
Lighter roasted coffees have slightly more caffeine for two reasons. First, less roasting tends to preserve the compound untouched. The longer the roast, the more chemical transformation in the beans, including loss of caffeine. Second, and this is an odd point, because most of us measure our coffee by volume and not by weight when brewing, lighter roasted beans are denser, and therefore pack more bean per unit volume that darker roasts, which are far less dense.
The Brewing is All
Assuming you don't enjoy the taste of super light roasted Robusta beans (mmm, tar!), the best way to optimize for caffeine kick is to think about how you brew (and how much you drink, of course). While espresso drinks have more caffeine per fluid ounce (80mg in a 2oz serving, or 40mg/oz), drip coffee has a standard unit of consumption (the "cup" versus the "shot") that's much greater: for example, a standard 12 ounce cup (120mg, or 10mg/oz). So even though there's less caffeine in each once of brewed coffee, we generally end up drinking more of it.
Your Body Has Final Say
Everyone has a unique metabolism, and so the physiological effects of caffeine vary by person, and by their current caffeine habits/tolerance. I'll testify to that firsthand; working in the Beanery means drinking a ton of coffee. At this point, I can have a double shot of espresso at 7PM and still sleep like a baby! Caffeine absorption also varies by the contents of your stomach; specifically, fats like those from the milk you might add to your brew are known to inhibit caffeine absorption.
If you just want to up your caffeine consumption, and skip the real complexities, my best suggestion is simply to drink more coffee (volume and variety), and to make each cup the best it can be.