Assess your strengths and weaknesses and focus on the former, while avoiding classes in the latter as much as possible. If you are good at math or science, aim for that area and pursue your creative writing urge at a weekend workshop.
Develop good organizational and time management skills. Get a year at a glance calendar and tape it to your desk. Mark in the dates your assignments are due. Don't leave papers until the last minute, and learn to finish drafts a day or so in advance to allow time for review. Don't lose valuable marks by handing assignments in late.
Read widely and take copious notes. Record direct quotes and citation information from every book, article and conference paper you read, even if you don't need it for this term. Develop a system of being able to quickly find your material -- by author or subject -- and you will save yourself hours trying to find the perfect quote for another paper six months from now.
Be proactive in your classes. Attend lectures, ask questions and be involved. Lecturers notice -- and appreciate -- students who participate, and this will be reflected when it comes to grades.
Develop your critical and lateral thinking skills. Engage in lively debates with other students and instructors. Present your ideas and be prepared to defend them. Then take the opposite point of view and argue that side. Being able to see all sides of an argument will elevate you to the head of the class.
Be consistent. Don't be a hard working student one week and slack the next week. Develop a routine and a pattern and keep on top of your work.
Stay healthy. Eat well, exercise and get enough sleep. No matter how brilliant you are, if you are sick and missing classes, a "good" degree will slip through your fingers.