My forearms are killing when doing anything involving bicep. So I want to strengthen them, plus my grip.... So I've bought hand grips. How often should they be used?
Definately heavy deadlift. Also anything else that forces you to hold very heavy weight in your hands for extended periods of time. Forget those silly grip things if you want a very strong grip.
Deadlifts, forearm curls, farmer walks, plate pinches all help. But recently I've gone off weights for more bodyweight stuff and randomly found a baseball while digging round my place. When I'm at home sitting on the computer I grip the baseball as hard as I can then roll it a bit and continue or switch hands. I've only done this for about a week so I can't say much but it does seem to have helped my grip strength. Edit: But, saying that, I woudn't really listen to a man who squeezes rock hard balls while logged on ESB.