In order for organic chemistry to make sense, you have to know valence bond and molecular orbital theories. How to draw structures, a full understanding of acids and bases - including + especially Lewis Acids + Bases. Basic thermodynamics concerning entropy, enthalpy, free energy, reaction progress, bond strength according to energy required to break/energy released when forming, etc. Basics with kinematics, and equilibrium constants (to know what parts of the molecule will react first). That will make the rest of it instinctive (aside from the must be memorized parts, like nomenclature).