Most Caribbean Party Drinks, Punches, coolers, etc... are usually found in a certain ratio, which I've found works very well. To make it easier to remember there's a poem, of sorts:

One Sour (Lemon Juice)

Two Sweet (Sugar Cane Extract, Dilute Molasses)

Three Strong (Jamaican or Puerto Rican Rum)

Four Weak (Water)

The easy way to put this into practice is to drop a handful (or two) of ice cubes in a pitcher and add the ingredients in their respective ratios. This yields a pleasant, yet potent concoction.