Best results are obtained when using egg whites that have been “aged” for a few days. Simply separate your egg whites and leave them at room temperature for 24 to 48 hours before using them. You can also age them for a few days in the refrigerator, but be sure to bring them to room temperature before using them.
Do not attempt to make your own almond powder by grinding almonds yourself. The result is likely to be too coarse and oily, which does not bode well for macarons.
Weigh your ingredients using a precision scale. Accuracy is critical! Even a little too much or too little can make the difference between success and failure
Be sure to let the unbaked macarons sit for at least 20 to 30 minutes before putting them in the oven. This can make a huge difference in how they turn out.
Place the baking tray inside another one to prevent the macarons from scorching, or keep the oven door slightly ajar with a wooden spoon to prevent the temperature from getting too hot.