Just_curious,
On the White's site, back in the day, there was a fella that posted a great deal of information about the XLT - what settings for what type of target/ground/coil/etc. It may still be there?
Yes it can be frustrating, the experience is our training and how we learn and asking questions on TNET will gain you some assistance. The "test garden" has all ready been suggested and it can be of great help especially if you can leave it there for a long time but of course that means you must have a map of what item (type of metal) is buried at what depth and with what other object (nails/pull tabs/bottle caps/a piece of tin can with a coin/etc.) As the years build on your test bed the readings are going to change!
Where to go? Hints: Where are the tallest, biggest trees in your area (go there) kids play in trees/people sit in the shade of trees/people bury stuff at or near a significant landmark (like a tree). The older homes in any town But you have to knock on the door and ask permission and then you have to not mess up their grass or yard!! Once I've located a target in the ground I use a brass probe to find and remove the target. this means that the hole is mostly below the grass with the surface hole about the size of my finger and the probe. A finger size hole closes up quite nicely BUT its slow and can be a real pain if there are rocks in the ground around the target. After I've used the detector to locate the target I will lay the machine on the grass near the hole and begin to probe for the target, often as I hit the target or get very close to it the detector will react. I suspect the detector leaves a charge in the ground around the target and the nearness of the brass probe to the target could release this charge, my guess.
So yes, a lack of good targets (silver coins, jewelry, a gold tooth Crown), can be a downer but learning your machine will help you to understand what it is telling you and it is telling you 'stuff' about every target. Learning comes with experience in the field and on a test bench while waving different targets past a coil (coil's) and from your own test garden. Then of course there is how you swing the coil: low and slow, low and fast or do you angle the coil to the ground at the start and end of your swings (not a good thing). Proper technique in the use of any detector is required, like X'ing the target to help locate it. Once I've X'ed the target I will use a thin pointed stick to mark the center of the X (or a plastic poker chip). Yes pin pointers are now common but then you've just dug a large plug in someone's yard or in the park's yard, using a brass probe is old school but it makes the homeowner happy. (Warning: ANY probe, brass rod or a screwdriver, can scratch a target, when that target is really good you do not want to have damaged it yourself. Technique is important!)
There is a lot to finding good places to detect and if you can make any home owner happy about the experience then they just might help you with the next neighbor. I used to mow lawns to assist in getting permission (found a silver Rosie at one home). I've returned things to the home owner. I try to make them happy about having me there. Yes lots of people have been around before you which means you must try harder and be more inventive in finding new possibilities in your area. Your detector thinks a nickel or a brass shell casing is gold so be careful when you set your machine to filter out 'junk metal'! You could start by running without any filters, find a target and then switch to one or another type of filter as this can also Tell You what is actually in the ground. Yes the XLT has icons of what the target could be but what the machine tells or shows you can depend on what filters you are using.
Finding a gold crown in soil with pea-gravel in it with a brass probe Was a pain in the back side but I kept at it as the machine told me the target was worthwhile but I'd used the machine enough to believe in it.
I used to be squirmy about being out detecting when lots of people were around. One morning I happened past the town chamber of commerce and noticed the sidewalk had been torn up (all the detecting magazines tell you to jump on sidewalk tear-outs) so I started swinging. ( Note: I was using earphones so I am listening intently to each whisper and I am Zoned Out to what is going on around me) So I get a few bottle caps one at a time, then I feel odd and look up to see the towns people have gotten out and I'm sensitive to this so I start to leave but I've still got my coil over the exposed dirt. As I'm heading for my ride I get a signal that is really loud. In my mind I go "What kind of a bottle cap is it this time"!? I pull the coil away and I can see the circle in the dirt. I push on one edge and my first gold ring rolls up. So much for feeling Odd when people are around.
Educate yourself by learning your machine and what each change to the settings is doing for or to you, this takes time but it will payoff. Best of success.................63bkpkr

Both rings were found with a detector. The Sharp Shooter ring is Aluminum and it's partially cracked. The Mickey Mouse ring is Sterling Silver no damage. I was offered more money for the Sharp Shooter ring. Yes, I retrieved the rings with my 6" long brass probe.
Addendum - I was reading over the full post from start to finish when this thought ran through my mind: Here is a real Clue - do your research and find Historical bus stop locations! Many will be under cement, sigh but again hit those sidewalk tear-outs, but for the ones that are not they could be valuable to you. True Story: one day in Palo Alto, CA I was doing my early morning detecting when I stopped at a bus stop that had an open slat bench sitting on top of dirt, just a tiny area. It was a gold mine for coins! My take from that spot paid for some detecting accessories. Be sure to make the ground look pretty after you are finished. 63