I find it's easier to brush JJ, my 5 month old Golden Retriever, when we're sitting outside on the front steps. He seems to be more relaxed outside, just sitting there taking in the sights, smells and sounds. This is when I can easily pull out a brush and brush him, without any treats even.
Brushing him inside wasn't as easy at first, but I learned to hold his patience with treats.
First, I had to introduce him to the brush by letting him sniff it out. I even used it on myself a few times before doing so on him, just to show him what it's used for and that it's not a toy to play with. Whenever he started biting at it, I would tell him to leave it. After about 3-4 days of this, I started to brush him with it. It was a process getting him use to it, but not one that was all that hard.
When it's time for him to get brushed, I tell him "time to get brushed". Then I put him in a "sit" as I stand in front of him. He gets a treat for doing so as I sit on the floor in front on him. I put a couple treats behind me on the floor, which he knows, of course, are there. If he jumps for them, I grab them and stand up real quick and put him in a "sit", again, and repeat the process. Once he's sitting nicely without going for the treats behind my back, I start to comb him. If he turns his head and goes for my hand or the brush. I stop, instantly and tell him no. After a few seconds I try again, if he can maintain a straight face and no biting for 2 seconds, he gets a treat, if he can keep it going for 6 seconds, he gets another treat, 10 seconds, another treat. Basically, a treat every 4 seconds until I'm done. If at any time he goes for my hand or the brush, I stop and give him a few seconds to realize what he did, why I stopped and why he didn't get a treat.
I am now pleased to say that I can brush JJ without any problems (for the most part at least). He knows if he sits there and behaves until I'm done, he'll be rewarded. I did the same thing when it came to drying him off with a towel and with that too he'll just sit there until we're done. I don't even have to use the treats anymore when it comes to towel drying.