Actually i try to go as low as i can on the handle. Some people would smash holding the cone while others would hold it at the bottom of the handle.
wen i do any shot except a backhand serve i hold the racket so that the bottom of my palm is just slighly touching the nub at the bottom of the handle. i play singles so i never really hold the handle up to much, wen i play mixed i hold the racket in the middle usually and shift around a lot during a rally its hard to say exactly, it moved up and down a lot in doubles
Backhand serve for me is always at the very top of the handle, with the thumb on the cone. For singles, every stroke with my hand on the bottom of the handle. For doubles, it varies; at the front, it's always at the top of the handle, in the midcourt it's around the middle, and in the back it's always at the bottom.
Here's how I do it.. Backhand serve: bottom of handle High serve: bottom of handle Clear: around the middle of the handle Smash: Between the middle and bottom of handle Slice drops: Between the middle and bottom of handle Lift: Bottom of handle Netdrops: around the bottom of the handle Drives: top of handle, near the cone I dont think about which grip to use before hitting.. I just naturally react to it.
there's no hard and fast rule, generally what suits you. just take into account that the lower you hold it, the harder you can hit, but the higher you hold it, the more control you have.
when smashing i always have my hand at the bottom of the racquet, when i grip it i make sure to make a bulge at the bottom so when i hold it there my hand doesnt slip off, this is the same for clears, drops and slices. when playing defensive shots i choke up on the racquet so that my thumb is on the cone, when playing net shots and all that my hand is on the bottom half of the racquet most of the time. net kills its always up near the cone. and for backhand shots its near the middle of the racquet.