I'm cheating here and reposting a section of a longer post for fellow guildie and Twitterite @tententacles. More protips available in these posts.
Gear Manager Is Your Friend . . .
. . . but I think it's a slight misnomer. I've tried to explain this before, but I don't think it was effective. You don't need multiple sets of gear for Gear Manager to be effective. Yes, you can carry around enough gear to effectively fill any role in a group, but chances are—at least early in the game—you'll want to simply upgrade gear you've got rather than accumulate different sets. On the other hand, you're quickly obtaining so many abilities that you'll soon have far more abilities than you have currently equipped. Some abilities are clearly useful for fighting single opponents, while others are far more suited to mowing down groups of mobs. Gear Manager comes in very handy for quickly flipping between sets of abilities even if you only have one real set of effective talismans. If you like macros, you can also set buttons to "/gearmanager use name" where "name" is the name of the saved gear/ability settings.
I've gone over skills and abilities in the past. I don't plan to write any guide showing any überl33t Flavor of the Month Deck that I think you should follow. I can only say that I am having little trouble so far with my chosen decks, and I only want to point you in the right direction. I linked this Deck Builder the other day, as well. It's awesome for seeing at a glance which active and passive abilities produce/exploit which states (Afflict, Weaken, Hinder, Impair) and what weapons may create synergies when used together. And it's accessible from inside the game, through the web interface (though this may not be ideal). You can also use whatever passive abilities you may have learned, regardless of whether you're currently using the weapon associated with them. So that Blade HoT passive can be used even if you're currently using Blood and Fists.