I"m pretty much beyond improvement, so I'll try to maximise what I had.....
First flat serves, 3 spots each side, maximum of 3 serves to each spot. The arm isn't good for more, neither is the shoulder, body, legs, or concentration. Hit only at maximum speed, since you play what your practice.
First topspin serves, 3 spots each side, maybe also 3 to each spot.
First twist serves, I need more work on, only go wide duece (me lefty), so can hit 7-10.
Second safe serves, aimed only left or reciever or right, maybe 5 each.
Second twist serves, shorter than for firsts, and on both sides, around 3-5.
Second high kickers, usually top/slices, 3 quadrants, maybe 3-5.
I'm pretty worn out after that ugly serving display.