What goose said.
But don't forget that as a hammerer your goal isn't necessarily damage as much as it is dizzy. Don't worry about critical draw as damage per hit isn't the hammer's thing, instead go for focus, earplugs/evade, handicraft/razorsharp, and THEN consider AUx (personally i go for adrenaline 2 but you better know what you’re doing, don’t say I didn't warn you).
The hammer and GS are very similar, the difference is your sacrificing
raw DPH for
(dizzy, fatigue, built in ESP for super pound, pretty high status effects, and mobility). The real damage dealer for hammer is the "golf swing" on the three hit combo NOT the super pound. Once it gets dizzy find the weak spot and golf swing the crap out of it. Keep in mind at all times that the tracker for KO damage will freeze until the monster recovers, and then it’s back to skull cracking. The super pound is for beating skulls as it rocks some serious KO damage.
Not saying the hammer can't do good damage but strive for those head knocks. Online it gets far more entertaining when you use focus and earplugs/evade. Focus will give you around two more dizzies if you’re trying for them (don’t worry about knocking around anyone on the head, they should know better) and thats when your friends get a whole 5 seconds or more to do whatever their sick little minds can come up with.
In short use focus, take shots at the head when possible, golf swing when it's dizzy, ad nausea.
If offline staying at the head when the monster is dizzy is not always the best move and online a good hammerer knows where the other hunters are. Whoever holds the hammer gets the head but make sure that's where you stay and everyone knows to stay off the head least they reap the whirlwind.
Now, get out there and beat some face!