Like Lorien said, you have to start somewhere! I think most hostesses and swappers know that there are beginners out there. What one person thinks is great, another might think is not so great. As far as art goes, it's all a matter of opinion as to what's "good" and what's not. One of the best ways to grow in your ability is to swap! Put out what you think is your best work and check out what you get back. You get new ideas, techniques, etc from swaps.
Here is a link to some stamping basics and what makes a "quality" card.
Making Your Swap Project
"Quality" is used here in terms of the paper used, straight cuts, the way the card was put together, etc.
Pick any swap and go for it!