This is my first year of hunting and i just got a grunt call.  Does anyone have some tips for grunting in a big buck?

Using grunt calls search 1  
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Here are 3 threads just in the last month to get you started.  For more, click on the search button right below the ads at the top of powwow.  Type in Grunt Calls.  Highlight powwow and hit return and you will find several pages of threads on using grunt calls.  I'm not a big fan of them.  They have their place and can help turn a deer towards you, but they can also get you busted.  Good luck!    

You said big. First thing is to adjust to the reed to a deep grunt. Just a tweak here & there to make it much deeper than usually comes from the factory. I've had great success some years & dismal others.