Syn's suggestion will help some, but you'll also snag up a lot more.
I find when the fish aren't feeding aggressively I will get a lot of "skin" hook ups, just barely hooked in the corner of the mouth usually... and not hooked into any solid jaw meat, just skin.
Leaving the fish in the water and grabbing it or netting it will help land these fish. Trying to pull the fish up into the boat or on shore will usually pull the hook out of the little bit of skin that is holding it. You also want to keep your line tight and don't give the fish any slack, as soon as they get just a little slack... they're GONE!!!
Sharpening your hooks as mentioned will also help.