We went to our first comp without ever even visiting one. We tried to do some turn ins like we'd seen online, but we really had zero idea what we were doing.
Everyone was extremely nice to us, and we didn't finish last in anything, and did ok in a couple of categories. Considering that we really knew NOTHING, we were thrilled, and we had a great time.
You won't embarrass yourself. People there will do worse things than you think you might. You may finish last, but you probably won't. You very much most likely won't kill anyone, and if you don't try to push it too much, you won't be DQ'ed.
Just remember the things that get you DQ'ed... using foreign materials, sculpting, pooling sauce... and you'll do just fine.