Well I don't know about that. It's not like newbies have a reputation that anyone cares about. It's okay to try anything once as long as you don't go back to the stuff that doesn't work that well.
if you're new and you show up, say WAR/WHM a couple times and then insist on keeping it when people suggest/tell you to change, there's a good chance of getting remembered. i've sort of /invite-blacklisted several people over the years, and leading all my XP parties i've heard a lot of "oh don't invite him/her, s/he XXXX". reputation is very important--and it doesn't have to be a big dramatic long term thing. as lots of you have experienced, if you do pick up parties, a lot of times you see the same people around your level (probably similar playtimes to you). if you come off as a stubborn noob/newb (love the distinction), they'll stop inviting you / accepting your invites. it's probably not stopping you from getting into a linkshell (though it might), but it is making your invites slower for the time being.
the bottom line is that you have to be open to the reasoning behind widely accepted choices in ffxi. the game is too team oriented to indulge everyone's learning process or quest to improve everything ("i'll show them how awesome i am when my new idea works!!"). innovation is great, and testing stuff yourself is great too. if you consistently test out things that people know are bad in a group context though, you'll get a deservedly bad reputation and have trouble getting people together to do the majority of the things in the game.
to put it another way, there's a lot of right and wrong answers in ffxi. if you end up not liking the right ones and preferring the wrong ones, a good idea is to quit and find a game more suited to your interests (or solo all the time). or find 6-18 people with exactly the same misconceptions about the game as yourself, but that's not very likely.
incidentally, the OP hasn't even started the game yet i believe. i'm giving a warning, not an admonishment. many, many, MANY people have walked down the path of "my ingenuity will revolutionize ffxi, behold, my idea for a new job/subjob combo!!!" and they get bad reps fast. sh*t, i still remember that DRG/MNK from 2005 on phoenix, tigerhawk.
edit: the other half of my warning is, ffxi is not a difficult game to learn, but there's lots to learn. you're well-served to take an open stance toward it at first, not an aggressive "no, i get it, THIS is the way it works, yeah!" kind of stance. Edited, May 30th 2010 5:19pm by milich