As a sophomore, you become eligible for a few more opportunities than you were eligible for in your freshman year. Continue to check this site for more opportunities. Also check with your department and the Honors Program for opportunities. You will want to use this year mostly to continue to build upon the work from your freshman year.
A few things to keep in mind:
Keep your grades up. Employers, graduate school admissions committees, and scholarship/fellowship committees like to see an upward trend in your academic grades. So, even if you had a bad freshman year, you can still turn it around in your remaining years in college.
Continue to work closely with faculty members. Work on building a relationship with current faculty members, but also work on maintaining contact with professors that were very meaningful to you in your freshman year.
Continue your research Also, start looking into REU programs through the NSF. These programs provide students with summer research opportunities at universities throughout the US. These tend to come with housing and a meal plan at the university as well as with a stipend. They also provide mentoring and graduate school and professional prep.
Have you made plans to study abroad? Do it. There are programs out there that provide study abroad funding. The Gilman Scholarship exists to help Pell recipients study abroad. The Boren scholarship helps students who intend on pursuing a career for the state department to learn a foreign language. Phi Kappa Phi also awards study abroad scholarships – you do NOT have to be in Phi Kappa Phi to get one.
Continue to Develop Leadership Roles. Take on more responsibilities in any campus organizations that you belong to and seek out a leadership position if applicable.
For more opportunities, check out: Sophomore Year