A couple years ago, a college student contacted me out of the blue and very politely asked if I could set aside some time to talk about my work and if I had any openings. I was so impressed with how direct and well spoken he was that I went to my HR Director and created an internship. I'll admit that many people are going to brush you off if you try this but, eventually someone will like the gumpshun.
On the point of grades; that may be something the HR people will screen but, I seriously doubt it. I've never asked a person about their grades and I've never been asked about mine. Whether or not you graduated (or are still attending) is the only thing anyone will really care about.
With resumes, write a cover letter tailored to each job you are applying for. Read up on the employer and find a way to work that information into your cover letter/resume. If I see a well written cover letter, I'll at least give the applicant an interview.
Once you're in the room, be confident. You wouldn't be there if they weren't considering you for the job. Make eye contact. Don't be afraid to show you have a sense of humor; nobody wants to work with a robot. After the interview, thank them for their time and don't be afraid to ask questions.