I would probably ask yourself what type of reactions do you feel least comfortable with. Alkenes, Alkanes, Alkynes, Aromatics, 1,2 additions and 1,4 additions, carboxylic derivatives ect. I think some of the more confusing ones come in organic 2 like reductions and oxidations of side aromatic side chains, Electrophilic Aromatic Substitution (what groups activate what groups deactivate), aldols, clasien condensations ect.
