Depending on what car u use, that will largely affect the way /
technique you turn.
Assume you are using the DC2 or RX7, basically,
a) Master the out-in-out method. ie: if turning right, before your
turn, keep EXTREME left, dive into the turn and when you exit, you
should also end out coming from the extreme left. When in the turn,
do your best to keep your car as near into the apex of the corner
as you can without crashing into it.
b) General rule is the faster your speed is while approaching a
corner, the earlier or sooner you must start committing yourself
into the turn.
c) If necessary, brake by tapping a bit and not jamming your whole
foot down on the brake peddle.
d) Try to achieve a slow (into the corner) and fast (out of the
corner) control
e) Dont go into a corner with full steering wheel lock.
f) On akina, most corners are done with a "double" turn of the
steering. 1st turn is gentle followed by a more committed
turn.
g) Myogi is a great way to practice as you only have 1 huge turn to
worry about. You can use that to practice and master your out in
out method. If you do it right, with the RX7, you should be able to
turn at 198-202 kmh (provided your car is full tune).
h) Dont brake unnecessary. Sometimes letting go of the accl early
is good enough.
Do note that different cars require different techniques but the
fundamental principles dont change or differ that much. Unless you
are on a bike. 
Hope this has helped.
