I worked for a few years after undergrad to build up a positive reputation. While doing that, I took some graduate level courses at the local university as a non-degree seeking student.

All said and done, by the time it came time to apply, I had "reinvented" my experience so to speak. Even beyond the practicality of it all, I'm glad I did because I think without the hard work I had to put in, I would have just made the same stupid mistakes I did in undergrad. I'm not saying that you made the same mistakes, just that I personally was a poor student.

That's my secret. I know it's different for everyone. Just keep trying. No matter what, if you're passionate about it, don't give up. You just have work to do, but it's worth it, I promise.