Methods for preparing waterborne heat seal coating compositions are disclosed, including (A) melt blending an ethylene vinyl acetate copolymer, a tackifier, and a wax in a first mixing apparatus to form a melt blend, (B) contacting the melt blend with an initial aqueous stream comprising a neutralizing agent, water, and a surfactant in an emulsification zone of the second mixing apparatus to form a dispersion, and (C) diluting the dispersion with water in a dilution zone of the second mixing apparatus to form the waterborne heat seal coating composition. Methods for preparing waterborne heat seal coating compositions are also disclosed, including (A) melt blending an ethylene vinyl acetate copolymer, a tackifier, and a wax in a mixing and conveying zone of a mixing apparatus to form a melt blend, (B) contacting the melt blend with an initial aqueous stream comprising a neutralizing agent, water, and a surfactant in an emulsification zone of the mixing apparatus to form a dispersion, and (C) diluting the dispersion with water in a dilution zone of the mixing apparatus to form the waterborne heat seal coating composition, wherein the length-to-diameter ratio of the extruder mixing apparatus is greater than or equal to 12 to 1. Waterborne heat seal coating compositions prepared according to the disclosed methods are also disclosed.