Matcha without a whisk.
Start by mixing it smoothly.
A bamboo chasen is made to combine matcha and water. When you do not have one, making a smooth paste with a small amount of water first can help matcha combine more easily with your drink.

Sift the powder first
Passing matcha through a fine tea strainer can help reduce lumps. Prepare a clean, dry bowl and spoon or a small whisk suitable for food and drinks.
Mix first with a little water
Rather than adding a full amount of water or milk at once, begin with a small amount of water. Stir gently with a spoon or small whisk until little powder remains at the bottom of the bowl.
Add the rest of your drink gradually
Add the remaining water or warmed milk a little at a time to the smooth matcha. Strength changes with the amount of matcha and liquid, so small adjustments make it easier to find what you enjoy.
Look forward to using a chasen too
A chasen lets you whisk matcha briskly with its bamboo tips. If you find yourself enjoying matcha regularly, try a bamboo whisk made for matcha and notice the difference in preparation.