Add mint, sugar, and lime to the glass. Use a sturdy highball glass.
Add the mint leaves, sugar, and lime wedges.
Muddle gently. Press the muddler down lightly 4–6 times. You want to release lime juice and mint oils without tearing the leaves into bits. If using simple syrup, muddle mint and lime first, then add the syrup.
Add rum. Pour in the white rum and stir to help dissolve the sugar and combine the flavors.
Fill with ice. Add ice cubes almost to the top.
Cubes melt slower than crushed ice and keep the drink bright.
Top with club soda. Pour in enough club soda to fill the glass, usually 2–4 ounces depending on your glass size and taste.
Lift and mix. Use a bar spoon to gently lift the mint from the bottom and pull it through the drink. This spreads flavor without bruising the leaves.
Garnish and serve. Add a mint sprig and a lime wheel if you like. Give the mint a quick clap between your palms to wake up its aroma before placing it in the glass.