How To Whip Egg Whites:

1. Start by double-checking that your bowl and beaters are perfectly clean. Even the slightest residue, or the presence of fat in any form (egg yolks, butter, oil, etc.) can make it impossible for your egg whites to whip properly. Wash and dry them thoroughly, and consider double-checking by running a clean kitchen cloth, paper towel, or cotton ball dipped in vinegar or lemon juice over the bowl and beaters to remove any lingering residue. 
2. Separate the egg yolks and whites. Place whites in your bowl and reserve yolks for another use. (Note: if ANY egg yolk gets into the whites, you’ll need to start over. Use the compromised eggs for scrambled eggs or omelets and start fresh.) 
3. Start whisking the egg whites on low speed with your mixer until the egg whites begin to foam (small bubbles will appear and the mixture will still be mostly clear).
4. Gradually increase the speed of your hand mixer to medium (or medium-high at the highest), until the egg whites are roughly double in volume and have turned white and mostly opaque. 
5. Start checking your peaks every minute or so until they’ve reached the right stiffness.

3 Stages of Whipped Egg Whites:

1. SOFT PEAKS: When a whisk or your beater is dipped into the whites and lifted up, the tip will look like a snowy peak. In soft peaks, the end or top of the peak will droop over (like soft-serve ice cream).
2. STIFF PEAKS: The top of the peak will hold its shape even when the whisk is rotated or moved. (You would even be able to turn your bowl upside down and the egg whites would hold their shape, though I don’t recommend trying this!)