Many factors affect your marketability as a law student seeking a summer job, and as a lawyer seeking your first associate position:
Some legal employers make interviewing decisions based on grades and may only choose to interview those students in the top 10% or 20% of the class. Good grades give you the option of choosing where you want to work, whether at a large or small law firm, in government practice or in a non-profit organization.
All employers value good research and legal writing skills. Employers look for evidence of good writing skills, either through participation in law review or another journal. Students in the top of the class are usually invited to participate in law review. Other students may have the option of "writing on" (applying to participate by submitting a writing sample). Willamette offers a number of other writing opportunities for students, including Willamette Law Online and the International Journal of Law and Dispute Resolution.
As a first year student, you won't have much choice in your curriculum. However, for your second and third years, select classes based on your career goals. Talk to attorneys in the field you hope to practice in and find out what classes they value when hiring new associates: What classes will they look for on your transcript? What classes could give you the edge over another applicant?
Most law students work during the summer after their first year and second year of law school. Some students also choose to work part-time during their second and third year of law school. Work experience can be an extension of the classroom, giving you practical application of the legal concepts you've only read about in the classroom. Work experience may also help you decide upon an area of legal practice.
You should make time to get involved in some extra-curricular activities. Employers like to see leadership ability, and your ability to balance extra-curricular activities along with work and classes lets them see that you'll be able to balance multiple tasks as an associate. Talk to attorneys or upper division students to decide which activities will best fit your interests and long term goals.