Look up book before you go to the class and watch youtube/khan academy/ videos for topics that you are not good at. Some universities offer free online classes for most of those topics and spend some time with them as well especially about bonding and acid/base. And, for Gen chem I and II you must work with numerical problems and practice them well.
View similar videos/ tutoring for O-chem as well. And, try to visualize the concept of bonding and reaction mechanisms.
I used to tutor Gen chem while i was at undergrad and I can help you some (Hope i have not forgotten) if you are dfw, TX area. Let me know.