The most important thing you can have will be properly leveled weapon skills, and proper atma.
The rest is really just common sense. Buy affordable upgrades to hold you over until you get the things that last you all the way.
What will set you apart, if you want to be useful, is having your skills capped and the atmas to make your job shine. If neither of these are viable, accept being gimped for a while, everyone does it at some point these days.
Think of it this way: Trying to make a level 76 warrior shine in a dom ops party is about like trying to make a level 61 warrior shine in a merit party of old. The maths are just too heavily stacked against you to compete. Being able to hit and do -something- will make it a lot more fun, though.. and prevent you from having huge backlogs of skillups to complete.
When you're too low to hit well, crit atma is more powerful than ever. I'd suggest Razed Ruins / Gnarled Horn and then an accuracy atma, until you're high enough level to start really hitting without those accuracy crutches. Visions/Scars areas will be more forgiving.
(For example, when my ninja was underleveled and underskilled, I was still hitting 0's a lot on sand sweepers, but crits were easily in the 70~ range. This was before I had RR or crit damage gear, even.)
Edited, May 28th 2011 3:26pm by ItsAMyri