If you are not using fresh citrus fruits don’t even bother to mix drinks. If you are going to be mixing cocktails, any cocktail, and yes this includes a classic Martini, Rum & Coke, or especially, especially a tiki or Polynesian drink, you need fresh citrus fruits, even if its just a garnish.
The very best martinis I ever had did not contain an olive, but a simple sliver of fresh lemon rind, rubbed on the rim of the glass, twisted, and dropped into the glass. Even something as simple as a rum and Coke can benefit from a squeeze of fresh lemon or lime. I prefer lemon, especially if its on the rim of the highball glass, I usually take it, give it a squeeze and drop it into the drink and stir it up and savor it sip by sip.
Any drink calling for rum surely has to have citrus in it. Don’t even dare think of using a sugary chemical sweet and sour mix, that would be blasphemy to the Polynesian Gods! You need fresh fruits. When it comes to Tiki drinks I like the more colorful citrus fruits like pink grapefruit or Sicilian blood oranges. Of course, regular grapefruits or oranges work just as well, but the reddish color of these fruits are more appetizing and exotic to the eye.
No matter where you live, nearly all fruits are available, lemons, limes, oranges and grapefruits, etc. The prices may more expensive depending on the season, but if you can’t have fresh, you can easily buy citrus fruits in the peak season. Buy a juicer or tool to squeeze the juice out of the fruit and freeze them in ice cube trays. Once frozen, transfer them into Tupperware containers or air-tight storage bags. The great thing about this is that ice cube trays provide you with exact measurements so when a cocktail recipe calls for half an ounce or 15ml of lemon, lime or orange juice, no need to measure, just add one cube and add to the cocktail shaker.
An important fact and tip is to know that the white part of the fruit which lies between the rind (outer skin) and the inner fruit is called the pith. This can be bitter, so you want to avoid using that if you are just using the rinds as a garnish or even the essential oils to twist over a Manhattan, Old Fashioned, Martini or any other drink.
If you really get ambitious, you will squeeze all the juice from your fruits, then put through a fine mesh strainer. While there is nothing wrong with the heavier pulp, you will certainly make better, smoother cocktails if you are only using the juice.
From these basics you can experiment and move on to more exotic forms of citrus such as Key Limes, Sicilian Blood Oranges, Pink Grapefruit, Meyer Lemons, etc.