What critical issues do you have? Is it still "psychology as a science", "free will and determinism" and "nature versus nurture"? If so I can try to point you in the right direction. Have a look at the developmental topics you cover in psychology when thinking about "nature versus nurture". It shows different theories and suggests whether psychologists see genes and instincts as being the key to development or the environment around them. Its also a good idea to focus on monozygotic (identical) twins and dizygotic (non-identical) twins. Look at them growing up together and apart.
"Free will and determinism" can have some connections with "nature versus nurture" as if nature and nurture both influence behaviour then a person doesnt have free will. Look at the different psychological approaches and see what they say. Do they see behaviour as being influenced by genes or the environment or do they see the individual as doing what he or she pleases. I think you'll find that it is hard to find a great deal of evidence for the free will side as even if people believe they have free will, they are still existing within the restrictions of society.
"Psychology as a science" is a total pain in the bum. I really cant help you very much with this one. It depends on the approaches used and the experiments used. Look at areas such as ecological validity and control in environments. Can you see the cause and effect?
Hope that helps a bit. If you have any specific questions, I'll try my best to help.