If i was to give one answer to that question it would be “change your attitude – make it positive” because i believe that a positive attitude towards not only sciences, but also all other subjects is the key. If you have the right attitude, concentrating in class, doing your assignments, extra reading and revisions will not be a hard task and all these lead to better performance. I advice against cramming too!
My attitude, in a lot of things in life is that if has been done before, then I can do it even better. If it hasn’t been done before, there have been many firsts and I could be a first too!
So, nothing is difficult, people have passed sciences before and so can you. Just maintain a positive attitude 🙂