|MadSci Network: Biochemistry|
In order to be a good chemist, and thus a good biochemist, you need a good physics background first. That is another thread.
First thing is a theory of why and how things work. Chemistry is were you first start to learn about how and why atoms interact to form compounds and then small molecules. Organic chemistry (o-chem) then leads to the next increase in size. In O-chem you start dealing with the interactions of molecules, ranging from simple (methane) to very complex (extracts from the bombardier beetle). Biochemistry moves into the realm of really large molecules, like proteins and such.
All of chemistry will give you a chance to practice hands-on work in the lab. This will range from knowing how to use a balance properly, to titration, identifying unknown compounds, and working with instruments that can identify DNA, to keeping a good notebook.
For a career in Forensic Chemistry, having a solid background in chemistry, biochemistry, and logic (both mathematically and philosophical) would be the most helpful.
[Moderator's Note: Biochemistry is the study of the chemical reactions and processes that make biological processes possible, so as Ara suggests above, chemistry (and ultimately physics) is at the heart of biochemistry. A forensics lab's use of chemistry allows it to identify, quantify, and classify all manner of biological and biochemical agents.]
Try the links in the MadSci Library for more information on Biochemistry.