Well i mostly do my combinations based on the animation, if its fluid for a continuation of another skill or not and its positive effects. Gotta do a pve and pvp build, but then im still learning, dont want to sound like some freaking expert or scientist of zerkers lol.
Best way to learn is through experience, keep playing it or just search some footage of berserkers in old videos of Bless to give you a hint on how you want to play with it.
Not that it will help though x.x

PS: i also challenge union players for 1vs1 so i can practice and see how i can fight against different classes, i keep dying in most of the cases but its good experience in the long run.