How Can I Ensure That I Am Learning History Accurately?

By considering the real source of the information you are reading. What is written in a modern history book is ordinarily about things that happened long before the author of that book was born. He must rely on information handed down in one way or another from the past. He may learn a few things from archaeology or geology. But the ideal source of information is usually a written record, and, preferably, one compiled by an eyewitness to the events he tells about.
For instance, if a modern historian alludes to the life of a certain Roman Caesar, you might ask yourself, Where did he get his information. Perhaps it came from the second-century Roman biographer Suetonius. Suetonius himself lived under the Caesars and also appears to have had ready access to the Imperial and Senatorial archives, as well as other contemporary documents. By reading the works of Suetonius oneself, of course, one learns what that ancient writer himself really said. One would thereby probably get to the closest available source of history about many Caesars.