it may not matter too much but heres what i do.
i try and imagine i have a key in my hand. i insert the key and turn it the way that feels natural. then that is the way i turn the tension tool... BUT
its not always correct...
ALSO:
if im turning the tool one way and 0 pins set and i turn it the other way and at least one pin sets than that is the correct way.
last but not least:
pick for awhile one way and if you get it good if you dont try picking the other way.
worst case senerio if you get it picked the wrong way you can use a plug spinner or pick it the other way.
some locks can be opened ether way. im not sure which locks your picking.
even some padlocks have a little faceplate with 1 or 2 quarter circles cut out of it making the key only turn one way. but these are obvious and if you had one of these you wouldnt have asked
ok hope i helped. good luck