I'd be interested in opinions on good ways (procedures) for checking
out the optimal brewing parameters for a new tea.

Here's what i have been doing (more or less). After each trial, I
record my personal rating of the result on strength (just right, too
weak, too strong), bitterness (none, low, high), and overall taste
(0-10).

1. Brew a pot using the vendor's recommendations, if any.

2. Eliminate bitterness first. If the result is bitter, reduce the
time until the bitterness goes away, keeping all other parameters
constant.

I sometimes have a little difficulty distinguishing between a brew
that is too strong and one that is bitter. I have a can of Earl Grey
Bravo from Adagio. The taste seems to vary more with amount of tea
that brewing time. If i use too much tea, I get a tea that is too
strong for my taste and seems "bitter", but I suspect it is really
just too much bergamot, which has a fairly strong (acidic) taste that
could seem bitter.