Accuracy at low levels is really lacking, so you'll have to get what you can take. The level 14 gloves with +3 acc and +3eva are the best gloves for THF pretty much up until level 70 when you can use war gloves. As already stated, there is the optical earring at level 10 which is a small boost to accuracy. After that, it's peacock charm at 33 (expensive and not entirely required) and sniper's ring at 40 (ignore the level 30 rings, not worth the gil and only used to craft sniper's). There are also enchantment rings which give +acc and +att at level 14, I'd look into buying those and using them during parties.
After that, you can also use DEX to increase you acc a little bit more, but not as much as straight acc will. Outside of rings and neck, you will not find much DEX at low levels. Fill earring(s) with +attack since besides optical, there is no +accuracy earring until 60+. Since you're a thief, you'll mostly be using daggers and swords pre-30, try using the ones with +acc and att, they actually tend to be the best up until 60ish. That mostly covers it, but if you'd like more in depth, I can name the best piece per slot.
Also, I was never very fond of optical earring. It's a decent tradeoff at low levels, 1 acc for 2 attack, but most neglect the attack gained from bone earrings so you're actually losing 3-4 attack for just that 1 acc.