Great question. I had this problem for a while. I was a total "hands-off" gentleman on dates and never got any second dates. We would just talk and talk like two friends and nothing would happen.
You have to touch the girl. Maybe touch her forearm once or twice while making a point. But the best advice I ever got was put your hand on her shoulder for a second or two when you get up to go to the restroom. Then say, "I'll be right back." I actually got that advice from a female, but it actually worked. The first girl I tried it with later ended up being the first I had sex with. (It took a few weeks; it wasn't a ONS.)
Touch or kino as we say is a must to break out of friendzone. Granted, she can STILL friendzone you based on looks despite touching her, but if she is attracted to you, then it will help make it a little more clear it's more than friends.
The other thing is don't let the date go on too long. Besides being a "hands off" gentleman nice guy, we would talk and talk and talk for several hours. I thought that was a good sign. It wasn't.
Actually, the only way to really know how the date went is to see how she acts towards the end when you are about to kiss her.
Bad signs:
Keeps lot of (phyiscal) distance between both of you
Walks fast to her car.
Says, "It was nice meeting you." <Delete her number ASAP if you hear this>
Turns so you can only kiss her cheek
Good signs:
Looks you in the eyes
Keeps talking to you in front if the car
Kiss on lips or better yet makeout
Ambiguous sign:
She says "Call me." <She may or may not answer>
Finally, to back-track a bit, a hug "opener" at the beginning of a date like Unchartered mentions in another post is very good and another tool to help avoid friendzone. See below.
http://www.sosuave.net/forum/showthread.php?t=208692