Originally Posted by
PigHog
Wow, good first attempt!
That cup will be too tall and narrow for whisking matcha properly, though. Try using a fairly steep sided bowl instead. Getting a proper whisking technique in the right amount of space will get rid of the grittiness and clumps. Also, I recommend sifting the matcha into your bowl (use a fine tea strainer or something) as it'll be less likely to clump when you add water.
I think 2 chashaku equals roughly 1 teaspoon, so try that. 60 ml sounds good -- I generally measure mine by eye these days. In my personal opinion it's better to have a little less water than too much.