Fill a cocktail shaker with ice. Pour in the vodka, orange liqueur, lemon juice, and simple syrup. Cover and shake vigorously until the shaker becomes cold.
Pour the sugar onto a small plate. (see note) Just a lemon wedge with a slit cut into it to rim a martini glass. Dip the rim of the upside down glass into the sugar.
Pour the lemon drop into the prepared glass. Garnish with a lemon peel on a cocktail pick or leaning on the rim of the glass.
To make a pitcher of martinis: Mix together 1 cup of vodka, 1/4 cup of orange liqueur, 1/2 cup of lemon juice, and 1/2 cup of simple syrup in a pitcher. (makes 4 martinis) Rim each glass with sugar, pour the martinis, and garnish with a lemon wedge. If you're drinking the martinis right away, add ice to the pitcher and give everything a stir to chill your drinks. If you're making the martinis ahead of time, skip the ice and place the pitcher in the fridge.
If you don’t want to make a sugar rim, I suggest adding another ounce of simple syrup.