Research or lookup volunteers are anxious to help others with their genealogy research, mostly because we've all been helped so much ourselves. But burnout is a problem that can easily be avoided with a little consideration for those trying to help you.
1) If you find yourself beginning your email with "Looking for any information..." stop right there. Consider this from the perspective of the volunteer. I have delved into whatever resources I had, and come up with a nice amount of information to send back to the requester, only to be informed that they already had that information. When you ask for help, rarely are you looking for "any" information. You've already got *some*... do your volunteer a favor and tell them what you have, and specifically what you'd like to find. Please be respectful of our time and effort.
2) Clearly state what geographic area and what time frame is involved, don't just give us a name. Many of us have our contact information on many state and county sites as volunteers; we don't automatically know where your ancestors are from or when they lived.
3) Read carefully what your volunteer is volunteering to do - if I have a particular book I'm willing to do lookups from, please don't ask me to go to the courthouse and get a birth certificate.
4) Please don't request information that you could easily find yourself using Google.
5) Most of us do not have infinite knowledge of or resources for your family or area of interest. Sorry, I do not know who paid for your great-great grandfather's grave stone. Sorry, I can't send you a photo of your great-grandmother's class reunion. Sorry, I don't know why your ancestors moved from Indiana to Illinois. (These are all real questions I've been asked.)
6) If you have a white list set up for your email, add the volunteer's email address to it. Don't ask us to fill out a questionnaire to be able to send you your results.
4) Most of all, please say Thank You! Chances are, your volunteer took time away from their own research to help you out, so acknowledge our efforts, even if we didn't find what you were looking for. A little appreciation is all the pay we get - please do give us that.