I own one basic (cheap) "metal finder" for property corners, dropped fasteners, nails in driveway, etc. Owned a nice nugget finder and found little so sold it. Very important to get a detector that works well in your geographic area. Find a dealer and talk with them so time spent is productive.
As a hobby I used to hunt for old bottle dumps. Access old "Sanborn Fire Insurance Maps" at the Library of Congress and find areas to search. Beware historic / archeology laws.
Beaches and areas where people congregate for picnics, fireworks, etc are usually good hunting too.