The classic Jamaican rum punch recipe is recorded in this simple rhyme:

"One of sour, 
Two of sweet,
Three of strong, and
Four of weak"

It works like this:

Sour is usually lime juice, but lemon juice or a mix is OK. 

Sweet is simple syrup or sugar, or any sweet liqueur.

Strong is rum, usually amber, but white is OK.

Weak is water, seltzer, fruit juice, or soda.

It doesn't matter if you use ounces or hogsheads as long as the proportions stay the same.

Combine them all and serve in tall glasses over ice. Garnish with fruit. A 10-ounce serving (less than a can of Coke) has three ounces of rum, so it's an easy-drinking but potent potion.

Here is the formula that I made for John's Jamaican Birthday Dinner.