Start here. These three changes solve 90% of weak-froth problems.

Water temperature: 160–175°F (70–80°C). Boiling water scorches the matcha, killing the proteins that create foam. If you don't have a thermometer, let boiling water sit for 2–3 minutes before using.

Sift your matcha. Clumps sink to the bottom and never aerate. Use a fine-mesh strainer and a spoon to push the powder through. Takes 10 seconds, makes a huge difference.

Whisk in a 'W' or zigzag motion, fast. Circles just spin the powder. A quick back-and-forth motion pulls air in and whips up a fine foam. 15–20 seconds is all you need.