The sidecar is nice, citrusy drink with brandy as its base spirit. Modern mixtures often have equal parts, I prefer a 3/2/1 mix:

3 parts Cognac
2 parts lemon juice
1 part Cointreau or triple sec

Mix the ingredients in a shaker half full of ice. Strain and serve with crushed ice in a sugar-rimmed lowball. Garnish with a strip of lemon rind.

Note that the original mixture, according to The Fine Art of Mixing Drinks, is:

8 parts Cognac or Armagnac
2 parts lemon juice
1 part Cointreau or triple sec