If you've never used a weight machine before, rather than mimicking the guy next to you or just guessing how to use it, look at the little diagrams provided on each machine. You may or may not know this but every machine states what it does and how you should use it. What's more? The diagram also shows you what muscles it targets. So take the time to read and learn the information provided to you before using an unknown machine. Even if you think you know what you are doing, it wouldn't hurt to double check yourself every once in a while.