As others have said, it's probably best to create a new character. I suggest a damage dealer, like a Death Knight or Eviscerator. Neither of those classes needs a lot of gear to kill quickly. The Evi is a single target class, so it kills slower than a DK. You will get the starter quests in Gludio and get some gear along the way to get you to Awakening at 85. From there you go to Aden to continue quests, including Exalted, that will get you more helpful gear and level you to 105 in a couple of days at most.
But to answer your question, you should already have some basic buffs on your ISS. You may need to go learn skills. You may not know this, but all of the basic buffs have been reduced to just 3-4 and everyone can learn them. The difference is that they will cost others more Spirit Stones than an ISS...generally speaking. If you don't have enough SP to learn everything, just go do War Torn Plains until you accrue enough.
Your bigger problem will be Runes. You will gradually earn some as you level, but you won't have all of your important buffs that require runes learned until you get your subclass leveled up, too. You can buy runes, but they're pricey.
Which brings us to an even BIGGER problem with L2 now. It's hard to earn adena by just normal hunting. There are drops of mats in some places, but not much else. When you get higher level there will be hourly instances where you can earn more adena than usual, but they are impossible to do solo for an ISS in basic/exalted gear.
Long story short, be prepared to play with your credit card.