If you have to tell people, or show them a card, then pretty much you're doing it wrong.
A few years ago now we were doing a band called Gomez. They showed up after a band field trip to Amoeba Records (which has a small stage people perform on) with a couple of kids and said they wanted them to do 30 min to open the show and that they would personally pay them. OK, what stars want we do. So, rolling our eyes - oh crap, street performers - we set them up, miked up the guitars and told the kids to play. It took about half a nano second for us to be amazed. Not only did all the stagehands go out in the audience (something most of us hate) and watch their entire set (unheard of) but they were so F-ing great that the promoter agreed to pay them out of his pocket and not the band's cut. (and that's like the earth spinning off it's axis and careening though the universe)
Point is, you don't have to tell people what a fricking awesome writer you are, wouldn't reading a couple of pages prove it? If you think you're the words greatest guitar player ever - then shut up and play your guitar. Should not your life and your work be the best proof of how smart you are, and not some card in your wallet?
I never have to tell people I'm just about the most awesome rock stagehand ever. I just have to tell them where I work and who I work for. The proof is always in the doing, not in the telling.