I have a 5-y.o. female Golden (she's actually a service dog, as I'm quadriplegic), and also live in a hot and humid climate, so I can definitely relate to the skin issues. I'd heartily second everything everyone else has posted: get rid of chemical irritants in the home, try various diets as skin and digestion go hand-in-hand (my Sydney is on Purina Pro Plan lamb & rice), and definitely use Advantage.
Also, I have a couple of thoughts from my own experience that might help:
1) During the warm months, keep your dog's coat clipped short. I know a lot of people are all about keeping a long, silky coat on their Goldens, but in warm climates it's just not that comfortable for many dogs, as the coat traps heat. You have to put your dog's needs above your own aesthetic pleasure. And make sure your groomer uses appropriate shampoos. Mine uses a gentle, baking-soda based shampoo that not only is soothing, but it helps her doggy-scent, too. I'll attach a photo of my girl so you can see how I keep her coat.
2) Goldens are notoriously neurotic and can get fixated on licking a particular spot long after the initial irritant is gone. The absolute best way to keep the obsessive impulses under control is by giving the dog something else to drain their physical and mental energy. Long, disciplined walks are a must (we take ours in the early morning -- it's not yet hot, and the mosquitos aren't as bad as near dusk). These are highly intelligent working dogs, and if you don't channel that energy, they'll find an unhealthy outlet for it. Even playing fetch can help. We play a game where I put rags in empty water bottles; one has a few drops of scented oil, and the others are clean. I hide all the bottles, and she has to find the right one to get a treat. If I've been sick for a few days and she hasn't gotten her normal levels of stimulation, she starts licking and chewing obsessively.
3) Make sure you've ruled out an underlying medical problem. Dogs often lick the skin over where something hurts, and the weather can certainly make certain conditions flare up.
4) Get your vet to refer you to a veterinary dermatologist (yup, they exist), or, if possible, a veterinary acupuncturist (yup, they also exist). I've had great success with acupuncture helping Sydney's anxiety when we travel.
Good luck!