My self, I havent really done much calling in the early season.. Ive called more during the later part of the season and Ive done very well. It hasnt always worked, but sometimes it does.. If you are able to snag a copy of the equipment issue of D&DH they have a great artical in there about calling deer. I read the article today, I believe it said try some light sparing (rattling) and some grunts.. I know it said sparing but Im not 110% on the sparing part.. I would deff check it out if your able to snag a copy.
"If I pull the hammer and shoot this young buck, he's dead. But if I pass on him, the next hunter might not shoot so straight."