Play the Game, Don't Work It
Both here in the forums and in the game I see many players agonizing over their choices. Pvp vs. non-pvp, book vs. staff, assassin vs. knight, so on and so forth ad continuum, ad nauseum.
Relax, especially during the Beta portion. Lineage 2, like all MMORPGs, is a game, not a life. First and foremost it is meant to be played, and played hard through many long hours of heart-stopping tension and knee-buckling relief. Dramatic dissappointment, heroic achievement, devastating loss, and stunning victory are all possible anytime, anywhere, and usually when you least expect it. The key element of any gaming experience has always been, and always will be, play.
And what exactly is play? Play, in the end, can and should be a kind of meaningless experimentation. Play means taking on a different role, a different set of attitudes, and a distinctly different viewpoint from the everyday. If you're not having fun, you're not playing, you're working, and in this case that means working with zero chance of any kind of real-world reward. Useless work is a fast highway to boredom, depression, and disillusionment. LIfe is depressing enough, why would anyone want to bring the stress of work into their leisure time?
So, my heartfelt advice is this: Stop working, start playing
Forget about what's best, strongest, or most likely to win. In Lineage 2 there is no winning and no losing; there is only the game. If you focus on winning, being the strongest, being the most powerful, and so on, all you are doing is transforming your play into work, and why would you want to do that?
If you can't decide between fighter or mage, create one of each and switch back and forth between them. True, other characters will advance faster, but what difference does that make? The important thing is you are developing a deeper feel for the mechanics of the game than any single character player ever will. If you play a mage on Monday, then take your fighter party hunting on Tuesday, you will be far better prepared to compensate for the mage's lack of toughness by spending as much time protecting them as you do seeking out new monsters. As a result, your party's healer will live longer, your party will fight harder, and everyone's game time will be more enjoyable.
The reverse is true as well. On Wednesday you can take the mage out with a party of strangers and you'll be far better at predicting when to sit back and heal, and when to finish off a monster too tough for the fighters to handle. As a result, your mage will gain a reputation for wisdom as well as skill, and more people will be happy to have you along with they head out after something really big, netting you an even bigger pay-off in cash, items, and those ever-important experience points.
The same holds true for every choice the game brings you. If you can't decide, then don't decide. Try every option, visit every city, make money, lose money, gain experience, lose experience, gain items, and lose them, do it all! You might never be the king of Aden, but hey, there can only be one king, it doesn't have to be you.
Play the game, don't work at it.