Use ice-cold butter cut into small cubes and keep your mixing bowl chilled; this creates a flaky, tender shortbread crust by preventing the butter from fully incorporating into the flour.

Always use fresh-squeezed key lime juice rather than bottled for superior tartness and flavor; if unavailable, regular Persian limes work well but use slightly less as they're more acidic.

Remove the crust from the oven when it's just set but still pale (about 12-15 minutes); overbaking will create a tough base that won't have the signature buttery, flaky texture.

Extract the lime zest using a microplane before cutting and juicing the fruit, as it's much easier to zest a whole lime and captures more vibrant citrus flavor in your filling.

Allow the bars to cool entirely at room temperature, then refrigerate for at least 2 hours before slicing; this prevents the filling from smudging and ensures you get clean, professional-looking portions.