Use eggs at room temperature, this way the whites will absorb more air and the meringue will be more stable. Eggs should be a week old or more, then the whites will be drier and whisk easier. Bowl for whisking should be grease free and wiped dry. You can degrease the bowl by wiping it with a slice of lemon. Carefully separate the whites from the yolks, not allowing the yolks to get to the whites. You can use your hands, passing the whites among your fingers (in this case, you need to thoroughly wash your hands, grease is our enemy).