Preheat oven to 350°F (175°C)
Line baking sheets with parchment paper or lightly grease them
Gather ingredients: butter (softened), sugar (granulated and/or brown), eggs (if recipe uses), vanilla, flour, baking soda and/or baking powder, salt, and mix-ins (chocolate chips, nuts, etc.)
Cream butter and sugar until light and fluffy
Beat in eggs (one at a time) and vanilla
Whisk dry ingredients separately (flour, baking soda/baking powder, salt)
Mix dry ingredients into wet ingredients until just combined
Fold in mix-ins (if using)
Scoop dough into balls (about 1 to 2 tablespoons each) and place on baking sheet with spacing
Bake 8–12 minutes, until edges are set and centers look slightly underbaked
Cool on the baking sheet 5 minutes
Transfer to a wire rack to cool completely