First of all I would recommend that you don't trust your ear as far as SC is concerned . It might help you with the easy questions but you will invariably get the harder questions wrong , always follow the RULES for every question !
Secondly , when you attempt SC questions , first read the original sentence and try to pinpoint what type of error ( if any) is present . If you are unable to do this , look at the answer choices and see how they are different from each other . This should atleast give you a 3-2 split and then proceed from there . Posted from GMAT ToolKit