For biochem, I would read the textbook on the material a couple times. Biochem is mostly about memorizing the structure of amino acids, carbohydrates, lipids, and understanding metabolic cycles. There is some problem solving, for example in knowing amino acid charges given a certain ph. But mostly memorization . Don't worry, it's not that much harder than ochem, if at all.
Biochem is not that difficult. The best thing you can do is read the chapter prior to class. Also as an above poster mentioned KHAN ACADEMY. They are an abundantly under utilized tool for undergraduates. Also use note cards. Just relax and you got this!
If it works for you, use flashcards for amino acids!! You can probably use them for carbs and lipids too. Focus on getting amino acids down, understanding how pKas work, and figuring out how pKas influence each amino acid's behavior in acidic/basic conditions. When you get to it in your class, understand the oxygen-hemoglobin dissociation curve really well and the effects of changes in pH, temp, etc! (It's great MCAT material, and a big part of biochem is figuring out what IS important to study and what's minutiae.)
And as someone above mentioned, find diagrams that link all the metabolic cycles together. You'll notice that the products of one metabolic cycle are often the starting materials for another cycle. You'll want to study each cycle on its own first, but eventually, you want to put the puzzle pieces together and see everything in its entirety.
You'll likely have to memorize steps/products in the metabolic pathways. Use pneumonics-they'll save you!! Draw the pathways out on a whiteboard or paper too.
If you've made it through ochem, you'll manage biochem just fine.