Fextralife is a great website for info about D:0S2.
I don't think they will cover accuracy though. For that, the forums are likely the best bet to get help.
That being said, here is even some info on accuracy. Your characters should start with a base accuracy of 95%. This does NOT mean they always have a 95% chance to hit as your target may have a dodge bonuses that reduces this chance.
The only thing I know that should decrease accuracy is if you are using a weapon that is higher level than your character. For example a level 2 character using a level 5 weapon would have a pretty big reduction in accuracy.
The two ways I know to increase accuracy are first from gear. Some weapons have bonuses to your accuracy, particularly crossbows often come with an accuracy bonus. The other way would be to put points into the weapon ability Single-Handed. However, this only works for characters using one weapon that is only a single handed weapon (sword/axe/dagger/wand).
Again, keep in mind that your target may have large dodge bonuses. So, even if you have a 130% accuracy, that doesn't always ensure a hit for every attack.
