My lvl 37 hunter who has the silencer gun with deadly scope attached is not criting as high as I have heard i should be. i have 213 agi and have been told that hunters with similar agi and the same weapon are critting over 800 but im only getting just over 500 at best usually around 300-400. Am I doing something wrong?

There are so many other factors involved besides just agility and the weapon you are using when it comes to higher crits. Yes, agility is like the life blood of any WoW Hunter but you also have to keep in mind the type of Hunter build you are using, the type of gear you have, and all the other stats besides agility. There is a whole lot of stuff that needs to be analyzed and once you study those things the answer you are looking for will become clear.

The best way to approach this would be to study the build, gear, stat points of one of your friends who is critting around 800 at your level and you will more than likely learn how to do it with your Hunter as well. With the new Armory available you can check pretty much any character's stats that you want to at World of Warcraft Armory. Find yourself a Hunter "Mentor" and analyze how they play, what gear they have, the most important stats to them, etc and just do the same thing. It's pretty simple but a lot of people underestimate this approach.

If I were you at level 37 I really wouldn't worry about it too much and continue to focus solely on leveling in order to hit level 70 and to be able to do some serious damage crits. Then find yourself a mentor and most importantly, enjoy yourself!