Play maps you already have S's on. Try to get half the number of misses you used to have. (94 -> 97, 96 -> 98, etc)
This is what helped me bring my accuracy up. Go through tons of maps after you get better accuracy, and if you run out of maps see how much better you got with a record you beat before. This pretty much brought all my 96's to 99's.
Also, if you haven't already, bring out the hit error meter thingy. Options -> Score meter type -> Hit error. Vertical lines represent when your hit was timed. White line in the middle = perfect, Left side = too early, Right side = too late. Watch your own replays, see where you end up, and adjust accordingly.
If you're talking about being unable to read a map (like, if it feels like putting HR on a map and you can't read AR10 like me), then you probably shouldn't play that map just yet. Play other stuff first.