Know math. A solid background in algebra, trigonometry and calculus are essential to getting a degree in electrical engineering. Algebra is used every day to describe and explain new concepts. An especially important algebraic concept in EE is the idea of "imaginary numbers." These are used to describe relationships between the components of alternating current and sinusoidal signals. Trigonometry is used to explain phase relations between voltage and current -- especially phase shift produced by passing AC through coils and capacitors. Calculus will be used to explain certain characteristics of semiconductors and other physics concepts. If you can not follow the calculus, the explanations will be opaque.
Learn enough physics to follow explanations about the behavior of atoms and electrons, including enough quantum mechanics to understand electrical and optical effects. You should have had one or more physics classes and have read several books on elementary physics before your first EE class.
Develop some facility with electrical components, including some skill in soldering, schematic reading and breadboard workups. If you do not have these skills, one of the best ways to get up to speed quickly is to build simple electronics projects.
Familiarize yourself with theoretical concepts like integrated circuits, op amps and digital logic. These topics are taught early in elementary EE classes.