Originally posted by: Mermaidman
LOL
Go ahead and wear your tennis shoes. It doesn't make you more likely to be searched. Now--no matter what kind of shoes you wear, do take them off before you go through the detector. Once, I asked TSA dude if I could where my sandals through. He said yes, then as soon as I passed through, he pulled me aside for a personal search EVEN THOUGH I DID NOT SET OFF THE DETECTOR. I asked him why and he said it was because I didn't take off my shoes . . .
Another thing to remember--Make sure you don't have any gum/candy wrapper that is metallic foil. I set off the detector once because of my gum wrapper!
Other tips:
Use online check-in
Choose seats near the back so you can board faster and put your stuff in the overhead bins (I assume you don't have elite frequent flyer status)
Take a bottle of water with you onto the plane in case you get thirsty
edit: Oh yeah, as Dragon said, keep your cool and fly stress-free!