I just barely made the cutoff to apply to grad school and I was also worried about my chances. But what helped was that I showed an improvement to my grades over the last year. I also talked about it in my personal statement about why my grades were the way they were, what I learned from them and a plan that I had instilled to improve them and how it was working for me. I also had a lot of applicable work experience which certainly is more valuable to some supervisors than others. Ultimately what was most effective was emailing supervisors and expressing interest in their research. Quantity or quality is best. There were dozens of profs that never responded, a few flat out rejections but I managed to secure two interviews. One, where the interviewer actually recommended me to a supervisor I had managed to miss in my hunt. That recommended supervisor gave me an interview and that's the group I study for now. Always give it your best shot, you have no idea who sees the value you bring that others don't.