tips on stopping biting/chewing

Question
Our 13 old golden retriever bites everything -  especially the hand that feeds her.  We've tried a firm "NO" while holding her jaws shut (firmly), we've tried spraying her with a spray bottle.  Both have had only a mild effect.

Can you recommend any special tricks?

Answer
Young Labs, which I know best, and other puppies tend to very bad about
biting.  You see a litter of them, and all the ones that are awake are biting
another one or themselves.  I am not even sure they realize that when they are
alone, if they quit biting, they would quit being bitten.  At 3 to 4 months
they are getting their adult teeth, and it seems they spend every waking
moment biting or chewing.  I maintain a Lab's favorite chew toy is another
Lab.  Otherwise they settle for any person they can.  They keep hoping to find
one that won't yelp and jerk their hand away, or growl "Bad dog." and clamp
their mouth shut.  Then offer a chew toy.  They keep trying despite hundreds
of corrections.   Another good technique is to quit playing and go away.   Be
sure to praise them when they are playing nice and not biting.

You just have to keep on correcting them, hundreds of times, not dozens.
Provide sturdy, safe toys such as Kongs and Nylabones.  Avoid things they can
chew pieces off and choke on them.  Keep them away from electrical cords.
Crates are essential for most young Labs and other dogs.

The pet stores are full of toys that many dogs will quickly chew up into
pieces they could choke on or cause intestinal blockages.  If you are not
there to watch, stick to sturdy stuff such as Nylabones and Kongs.  Keep a
close eye on chew toys and quickly discard anything that is coming apart in
pieces.  Rawhide is especially bad because it swells after being swallowed.
These problems are the worst with, but not limited to, large, aggressive
chewers such as Labs.

Ropes from the pets' store quickly turn to hazardous shreds.   Ones I made
lasted much better.   Go to a hardware or home center that sells rope by the
foot.  Buy 2' of 3/4" poly rope.   Melt the ends, and tie  knots in it.   Get
them as tight as possible, put it in a vise and pound it with a hammer.  Watch
carefully, and be ready to discard when it comes apart.

Everybody the dog has contact with must take a 0 tolerance stand on biting.  It takes a long time, and every time somebody lets the puppy bite, without correction, it makes it harder.  The yelp, like a litter mate bitten too hard, and jerk your hand away is very effective with some.  Just how you correct her is less important than the absolute consistancy.  It you add a little vinegar or lemon juice to the water in the spray bottle, it helps.  If a puppy is removed from its litter before 6-7 weeks, it can be even harder.  

One thing that may help now is a small cloth tied in knots.  Wet it and freeze it.  The cold helps soothe gums where the adult teeth are erupting.  With 2 of them, one can be refreezing while she chews the other.