A chef is also a scientist. The tools and methods used by a chef are very similar to those used by a scientist. We mix, shake, stir, separate, heat, cool, dissolve and measure. Although trial and error is usually the best way to learn, it can be expensive - that's why we have cookbooks. If you try something from a recipe and it doesn't come out perfectly - don't give up.
Cooking takes patience and practice.
It is best to use eggs at room temperature. When whipping egg whites make sure that there is no yolk in the mixture at all. It pays to separate them one at a time rather than into one big bowl. When heating, cover the pot to prevent the skin from forming. Heat it slowly or else it will burn or scorch.