Couple of things to try?:

Food:Adjust your lightning to within the range of the acc food you're using (as per previously linked chart) to get a slightly higher boost.

Weapon:Are you moving as you fight the mob? I have noticed that attacking from the sides/back and from a longer distance increases my accuracy.

Gear:Only suggestion here is optimal rank. I'm not suggesting you are a culprit, but I have seen people who run around in R45 gear at R20 and ask people why their stats/def/etc suck.