The fact of the matter is that although weighing ingredients, as commercial and many professional bakers do, is the most accurate way to measure, the American home baker still relies on volume measurement most of time. I do it and I bet you do too, so at the very least we need to know how to measure dry and liquid ingredients as accurately as possible.
This starts with equipment.
Dry Measuring Cups:
You might think a 1 cup dry measuring cup is the same no matter the brand or place of purchase, but unfortunately this is not the case. There are industry standards for weights and measures and not all measuring cups are designed to these specifications. If you purchased your set at the dollar store, I would toss it. If it is old, of unknown provenance and/or dinged and dented – toss it. The reputable brands that I use are Cuisipro and the ones sold by King Arthur Flour. You should have a set that includes ¼-cup, 1/3-cup, ½-cup and 1 cup at the bare minimum. I Strongly suggest that you also purchase a set that includes 2-tablespoons, 2/3-cup and ¾-cup. A 2-cup measuring cup is also extremely handy. The reason for the many different, specific sizes is simple. Let’s say a recipe calls for ¾-cup of sugar. If you use a ½ cup and a ¼-cup (or lets say you can only find the ¼ cup and measure the sugar three times) you are measuring multiple times to get to that one ¾ cup amount. Since volume measurement is not exact, every time you measure, there is room for error; therefore by measuring once with a ¾ cup measuring cup you at least eliminate the variables inherent with multiple measuring. This might seem like a subtle nuance, persnickety even. It is, but I assure you it is this kind of attention to detail that will help you produce the best baked goods. Invest in these tools now, treat them well and they will serve you well for years to come.
Years ago, I read a tiny article in Gourmet magazine that, quite frankly, spun my head around and shocked the heck out of me. It changed me permanently; I am not being overly dramatic. It detailed how every person in the office brought in their set of measuring spoons. They then systematically measured 1 tablespoon of salt with all the sets and weighed each one. The results were so varied as to be inexplicable (or so they thought) and horrifying. They, like you and me, had been operating under the assumption that if someone made a set of spoons, that the tablespoon would be a “true” tablespoon. I cannot find the original article, but what I remember is that they found that their measured tablespoons of salt ranged from 6 grams to 14 grams. That’s right. The weights varied by more than 100%. How could this be? Apparently, if you want to carve a set of measuring spoons out of wood, or mold them out of ceramic clay (I am assuming you do not have metalworking equipment at hand) and put them up for sale, you could. You could make that tablespoon to be whatever size you wanted and call it a tablespoon. OK I am being dramatic here, but the point is that while there are industry standards, no one is bound to adhere to them when it comes to producing measuring cups and spoons for the home baker. We have to rely on reputable companies who take measurement seriously. I use Cuisipro spoons, which are available in standard1/8-teaspoon, ¼ teaspoon, ½ teaspoon, 1 teaspoon and 1 tablespoon sets as well as a set offering A Pinch, 1/8-teaspoon, 2/3-teaspoon, 1 ½ teaspoons and 2 teaspoons sizes. See explanation above in section on Dry Measuring Cups as to why I recommend as many sizes as possible.