I've got a story along these lines I'd like to share.
Had a friend who owned a metal detector shop here in town, and there was an older man who came in about every month or two and purchased a new detector. After about six months he came in the final time, and he was steaming! He said "I've spent over $2,000 on metal detectors here and all I have to show for it is a dollar in pocket change and some junk!" What could the store owner say? He had perpetuated this horrible trend by allowing the man to purchase machine after machine in the name of "sales," and never asked any questions!
I'll echo what was said before in the replies to this post. Know your machine. I've had a Fisher 1266-X for almost 15 years now, but it took me a year to find my first old coins and silver coins. In the beginning, dig everything! I incorrectly assumed during that first year that coins would sound the same regardless of age or depth (the instruction manual was decidedly vague on this important point, and obviously not written by someone who "knew" the machine). But there's really more to it than that. Realizing things about where the most productive places to hunt are is extremely important. This was also a facet of my beginner's ideology that was fundamentally flawed. I thought that any old, prominent site was good. My mind went off into fantasy-land whenever I saw a historical marker. Now don't get me wrong. Those obvious spots have been productive for me occasionally, but very rarely. Realizing that what is obvious to us is probably obvious to everyone else with a detector is a big step. After the research bug bit me, my finds took off. I started locating places that weren't there anymore (with no signs remaining of their existence). All of a sudden I had Morgan Dollars, Barber and Seated Halves, Civil War relics, and the like. Now each site took a lot of research, and even in some cases a bit of hit-and-miss in the field. I recall some weeks spending more time in the library than out with the detector! My third problem was that I didn't know what to do about a site being previously hunted, except for to give up. Wrong idea! I have found some great coins at worked out sites. I remember one area where all the obvious places in the immediate vicinities around churches/picnic groves/etc where exhausted, but the brushy areas and fringe areas gave up Barber coins and Indian head pennies!
So in summary, I've decided that metal detecting is a mental exercise at least as much as it is a technological one.
1. (As others have said) know your machine.
2. Find places that are less obvious, and do research.
3. There's no greater thrill than making a great find in a "worked out" site. When you come across a place others have hit, outsmart them!
I wish someone had told me these things when I was a Newbie.
Good Luck, and keep us posted!
Buckleboy