It depends on the type of cache you are lookiing for.
If it is a small money cache that was hidden by someone at a house, start by looking at what you could see from the front door. If you buried you money, wouldn't you want it where you could watch over it? I would.
Under the front door step, in a loose rock in the fireplace. These are just ideas for you to start with.
Now if you are looking for a "large lost cache", research, research, more research, then a field trip to eliminate places and get down to a couple of sites. Now more research and field trips to eliminate more sites.
Once you have it down to one site, then you start doing field trips over and over to it.