Science has given us a high-technology society. And, scientists usually have the best high-tech toys. So, most people imagine that fossil hunting involves radar, or something.
Sadly, it's not true. Fossil hunting mostly consists of people walking around, looking carefully. Sometimes they hit at a surface with a little hammer. But they don't do real digging until after something is spotted.
Where do they walk? Well, for starters, there's no point in going to a place that's being buried. You want a place where there's erosion, so that old rock is coming to light. Scientists often visit the same area every year, looking for buried things that are beginning to be exposed, but haven't yet been damaged by the erosion.
There are a number of tricks of the trade. A method taken from gold prospectors is to look for fragments in a dry rill channel. After you find something, search upstream for more. When the trail of fragments peters out, you search upslope - for the mother lode, as miners put it.
Unfortunately, these searches favor the discovery of large fossils, and it's entirely too easy to think that large fossils tell the whole story. At one time, fossil hunts in the Badlands of South Dakota had mostly turned up alligators and turtles. Some geologists concluded that the area had been mostly rivers and swamps. That idea was overturned by a study of fossilized ant mounds, which found that the ants had gathered minute bones and teeth to protect their nest openings. The bones were all from grassland burrowers such as gophers and mice. It is now known that the area was mostly grassland, with only a few rivers and swamps.