5) Finding good sources of caffeine
Despite the huge variety of sources of caffeine – including caffeinated soap, candy, and of course chocolate – the optimal use of caffeine is likely to involve small, hourly doses along with some cardioprotective agent. Given the high solubility of caffeine, absorption time should not be an issue (but if for some reason it is, try gum).
Otherwise, why not enjoy a cup of green tea (coffee-flavored, if you must), as the Chinese have for nearly 5000 years? It’s hard to come by a better longitudinal study than that.