for the record, if there is a harbor freight around, pick up the torque wrenches on one of their "biggest sales ever!!!!" you can score a 1/4, 3/8, and 1/2 drive for $11.99 each. i turn wrenches for a living, and have used all three sizes for three years with no issues. Rebuilt 15 liter engines, each year i have them calibrated when the guy comes around to our shop. each year they check ok. i used to catch flak about the cheap wrenches, till a friend had an 800 buck digital snap-on and under torqued a bolt, causing a little over $20,000 in repairs...
another good brand i have had good luck with was a gear-wrench 1/4 drive.
you dont have to break the bank to buy a good torque wrench.
like @
adouglas said, always zero them back out. dont drop them, and if in doubt, check it against a known good wrench if you cannot get it calibrated by someone.
Personally, i have not worried about using the wrench in reverse, to torque, not breaking a bolt loose. they say not to, but what do you do when you have to torque a bolt with reverse threads???
with all this said, this is a precision tool, if it is not precise, its worthless. so take care of it, and double check it's accuracy before relying on it for precision work