College classes are much more work than your high school classes. On average students take 4 or 5 classes a semester. (not more than that) Start out your first semester slow with one major in mind and take your general education requirements. See how you do and adjust accordingly. That first semester is transition time so that you get used to the academic load and managing living on your own. For some students it is a difficult adjustment. Focus on getting those grades to maintain your scholarship.
After that first semester then consider do you want to do a double major or one major and one minor. Assess what is realistic and feasible to achieve. Focus on quality of experience instead of quantity of courses. Utilize summers to get internship experiences to expand your knowledgebase and build your resume. Outside of your classes you will want to get involved on campus or possibly look at other learning opportunities like study abroad.