The whisk is the first thing to give you trouble. If you're using a bamboo whisk, it's easy to bend the tines by pressing too hard against the bottom of the bowl. That ruins the whisk's ability to aerate. Use a gentle hand and let the whisk do the work. Alternate: a milk frother is practically foolproof—just dip it in and pulse for 10 seconds.

Another failure point: measuring. Eyeballing matcha leads to a cup that's either too weak or too bitter. Invest in a small digital scale or use a proper 1/2 teaspoon measure. Consistency matters more than speed.