Add the 1/2 teaspoon of salt to your egg whites. If you have cream of tartar available (this is optional but genuinely helpful), add 1/4 teaspoon now. These ingredients stabilize the protein structure you're about to create. Using an electric mixer on medium-high speed, begin beating the whites.
Within about 30 seconds, you'll notice foaming. Continue beating. Within 60 seconds, soft peaks should form—when you lift the beater, the peaks will droop and fall back into the mixture. Keep going. After about 2-3 minutes total, the whites should reach stiff peaks—when you lift the beater, the peaks stand straight up and hold their shape. This is your target.
Here's the sensory test I use: tilt the bowl slightly. If properly whipped egg whites slide at all, they need more time. When they're ready, they'll stay put even when tilted. You'll also notice the texture transforms from clear and glossy to opaque and matte, almost like shaving cream.