My most important piece of advice, DON'T give up!!! Dedication, perseverance and good old fashioned hard work will help you be successful!! Here are a few other tips to help you....
Don't get behind on your notebook!!!
Review your notes daily for 7-8 minutes. Add notes in the margins, color and diagrams.
Ask questions if you don't understand something.
Form a study group. Find a few reliable friends that you can study with. You should meet regularly to discuss the material, review major concepts and vocabulary. Don't just cram for tests!!
Study the vocabulary! You must be able to define, explain and apply the words. (memorized textbook definitions will NOT get you very far!)